题目链接： https://ac.nowcoder.com/acm/contest/5670/E
题意：给出一个置换P，问1~n这n个数有多少种排列，能经过若干次p的置换变为有序序列？答案对10^N取模
题解：找出数组中，每一个环得长度，求所有环的长度的最小公倍数
难点：大数模板，取环长度
计算环长度模板
1 for(int i=1; i<=n; i++)
2 {
3 if(!vis[i])
4 {
5 num.clear();
6 int tmp=i;
7 while(!vis[tmp])
8 {
9 vis[tmp]=1;
10 num.push_back(tmp);
11 tmp=a[tmp];
12 }
13 f();
14 }
15 }
View Code
大数模板
1 #define MAXN 9999
2 #define MAXSIZE 500 //最大长度
3 #define DLEN 4
4 class BigNum {
5 private:
6 int a[21000]; //控制大数的位数
7 int len; //长度
8 public:
9 BigNum() { len = 1; memset(a, 0, sizeof(a)); } //构造函数
10 void XD();
11 BigNum(const int);
12 BigNum(const long long int);
13 BigNum(const char*);
14 BigNum(const string&);
15 BigNum(const BigNum&); //拷贝构造函数
16 BigNum& operator = (const BigNum&); //重载赋值运算符
17 BigNum& operator = (const int&);
18 BigNum& operator = (const long long int&);
19
20 friend istream& operator >> (istream&, BigNum&); //重载输入运算符
21 friend ostream& operator << (ostream&, BigNum&); //重载输出运算符
22
23 template<typename T> BigNum operator << (const T&) const;
24 template<typename T> BigNum operator >> (const T&) const;
25
26 BigNum operator + (const BigNum&) const; //重载加法运算符，大数加大数
27 BigNum operator - (const BigNum&) const; //重载减法运算符，大数减大数
28 BigNum operator * (const BigNum&) const; //重载乘法运算符，大数乘大数
29 bool operator > (const BigNum& b)const; //重载大于
30 bool operator < (const BigNum& b) const; //重载小于
31 bool operator == (const BigNum& b) const; //重载等于符号
32 template<typename T> BigNum operator / (const T&) const; //重载除法运算符，大数除整数
33 template<typename T> BigNum operator ^ (const T&) const; //大数的n次方
34 template<typename T> T operator % (const T&) const; //大数对int取模
35
36 template<typename T> BigNum operator + (const T& b) const { BigNum t = b; t = *this + t; return t; }
37 template<typename T> BigNum operator - (const T& b) const { BigNum t = b; t = *this - t; return t; }
38 template<typename T> BigNum operator * (const T& b) const { BigNum t = b; t = (*this) * t; return t; }
39 template<typename T> bool operator < (const T& b) const { BigNum t = b; return ((*this) < t); }
40 template<typename T> bool operator > (const T& b) const { BigNum t = b; return ((*this) > t); }
41 template<typename T> bool operator == (const T& b) const { BigNum t = b; return ((*this) == t); }
42
43 bool operator <= (const BigNum& b) const { return (*this) < b || (*this) == b; }
44 bool operator >= (const BigNum& b) const { return (*this) > b || (*this) == b; }
45 bool operator != (const BigNum& b) const { return !((*this) == b); }
46
47 template<typename T> bool operator >= (const T& b) const { BigNum t = b; return !((*this) < t); }
48 template<typename T> bool operator <= (const T& b) const { BigNum t = b; return !((*this) > t); }
49 template<typename T> bool operator != (const T& b) const { BigNum t = b; return !((*this) == t); }
50
51 BigNum& operator += (const BigNum& b) { *this = *this + b; return *this; }
52 BigNum& operator -= (const BigNum& b) { *this = *this - b; return *this; }
53 BigNum& operator *= (const BigNum& b) { *this = *this * b; return *this; }
54 template<typename T> BigNum& operator /= (const T& b) { *this = *this / b; return *this; }
55 template<typename T> BigNum& operator %= (const T& b) { *this = *this % b; return *this; }
56 template<typename T> BigNum& operator += (const T& b) { *this = *this + b; return *this; }
57 template<typename T> BigNum& operator -= (const T& b) { *this = *this - b; return *this; }
58 template<typename T> BigNum& operator *= (const T& b) { *this = *this * b; return *this; }
59 template<typename T> BigNum& operator ^= (const T& b) { *this = *this ^ b; return *this; }
60
61 BigNum operator ++ (int) { BigNum t = *this; *this += 1; return t; }
62 BigNum operator -- (int) { BigNum t = *this; *this -= 1; return t; }
63 BigNum& operator -- () { *this -= 1; return *this; }
64 BigNum& operator ++ () { *this += 1; return *this; }
65
66 template<typename T> BigNum& operator <<= (const T& b) { *this = *this << b; return *this; }
67 template<typename T> BigNum& operator >>= (const T& b) { *this = *this >> b; return *this; }
68
69 template<typename T> BigNum friend operator + (const T& a, const BigNum& b) { BigNum t = a; t = t + a; return t; }
70 template<typename T> BigNum friend operator - (const T& a, const BigNum& b) { BigNum t = a; t = t - b; return t; }
71 template<typename T> BigNum friend operator * (const T& a, const BigNum& b) { BigNum t = a; t = t * b; return t; }
72 template<typename T> friend bool operator < (const T& a, const BigNum& b) { return b > a; }
73 template<typename T> friend bool operator > (const T& a, const BigNum& b) { return b < a; }
74 template<typename T> friend bool operator <= (const T& a, const BigNum& b) { return b >= a; }
75 template<typename T> friend bool operator >= (const T& a, const BigNum& b) { return b <= a; }
76 template<typename T> friend bool operator == (const T& a, const BigNum& b) { return b == a; }
77 template<typename T> friend bool operator != (const T& a, const BigNum& b) { return b != a; }
78
79 void print(); //输出大数
80 int Size(); //返回大数长度
81 int the_first(); //返回第一个数字
82 int the_last(); //返回最后一位数字
83 int to_int(); //转化为整数
84 long long int to_long();
85 string to_String(); //转化为string类型
86 //char* to_char();
87 };
88
89 BigNum::BigNum(const int b) //将一个int类型的变量转化为大数
90 {
91 int c, d = b;
92 len = 0;
93 memset(a, 0, sizeof(a));
94 while (d > MAXN) {
95 c = d - (d / (MAXN + 1)) * (MAXN + 1);
96 d = d / (MAXN + 1);
97 a[len++] = c;
98 }
99 a[len++] = d;
100 }
101 BigNum::BigNum(const long long int b)
102 {
103 long long int c, d = b;
104 len = 0;
105 memset(a, 0, sizeof(a));
106 while (d > MAXN) {
107 c = d - (d / (MAXN + 1)) * (MAXN + 1);
108 d = d / (MAXN + 1);
109 a[len++] = c;
110 }
111 a[len++] = d;
112 }
113 BigNum::BigNum(const string& s)
114 {
115 int t, k, index, l, i;
116 memset(a, 0, sizeof(a));
117 l = s.size();
118 len = l / DLEN;
119 if (l % DLEN)
120 len++;
121 index = 0;
122 for (i = l - 1; i >= 0; i -= DLEN) {
123 t = 0;
124 k = i - DLEN + 1;
125 if (k < 0) k = 0;
126 for (int j = k; j <= i; j++)
127 t = t * 10 + s[j] - '0';
128 a[index++] = t;
129 }
130 }
131 BigNum::BigNum(const char* s) //将一个字符串类型的变量转化为大数
132 {
133 int t, k, index, l, i;
134 memset(a, 0, sizeof(a));
135 l = strlen(s);
136 len = l / DLEN;
137 if (l % DLEN)
138 len++;
139 index = 0;
140 for (i = l - 1; i >= 0; i -= DLEN) {
141 t = 0;
142 k = i - DLEN + 1;
143 if (k < 0) k = 0;
144 for (int j = k; j <= i; j++)
145 t = t * 10 + s[j] - '0';
146 a[index++] = t;
147 }
148 }
149 BigNum::BigNum(const BigNum& b) : len(b.len) //拷贝构造函数
150 {
151 memset(a, 0, sizeof(a));
152 for (int i = 0; i < len; i++)
153 a[i] = b.a[i];
154 }
155 BigNum& BigNum::operator = (const BigNum& n) //重载赋值运算符，大数之间进行赋值运算
156 {
157 len = n.len;
158 memset(a, 0, sizeof(a));
159 for (int i = 0; i < len; i++)
160 a[i] = n.a[i];
161 return *this;
162 }
163 BigNum& BigNum::operator = (const int& num)
164 {
165 BigNum t(num);
166 *this = t;
167 return *this;
168 }
169 BigNum& BigNum::operator = (const long long int& num)
170 {
171 BigNum t(num);
172 *this = t;
173 return *this;
174 }
175 void XD()
176 {
177 cout << "A hidden egg! Good luck for u!" << endl;
178 }
179
180 template<typename T> BigNum BigNum::operator << (const T& b) const
181 {
182 T temp = 1;
183 for (int i = 0; i < b; i++)
184 temp *= 2;
185 BigNum t = (*this) * temp;
186 return t;
187 }
188 template<typename T> BigNum BigNum::operator >> (const T& b) const
189 {
190 T temp = 1;
191 for (int i = 0; i < b; i++)
192 temp *= 2;
193 BigNum t = (*this) / temp;
194 return t;
195 }
196
197 BigNum BigNum::operator + (const BigNum& b) const //两个大数之间的相加运算
198 {
199 BigNum t(*this);
200 int i, big;
201 big = b.len > len ? b.len : len;
202 for (i = 0; i < big; i++) {
203 t.a[i] += b.a[i];
204 if (t.a[i] > MAXN) {
205 t.a[i + 1]++;
206 t.a[i] -= MAXN + 1;
207 }
208 }
209 if (t.a[big] != 0)
210 t.len = big + 1;
211 else
212 t.len = big;
213 return t;
214 }
215 BigNum BigNum::operator - (const BigNum& b) const //两个大数之间的相减运算
216 {
217 int i, j, big;
218 bool flag;
219 BigNum t1, t2;
220 if (*this > b) {
221 t1 = *this;
222 t2 = b;
223 flag = 0;
224 }
225 else {
226 t1 = b;
227 t2 = *this;
228 flag = 1;
229 }
230 big = t1.len;
231 for (i = 0; i < big; i++) {
232 if (t1.a[i] < t2.a[i]) {
233 j = i + 1;
234 while (t1.a[j] == 0)
235 j++;
236 t1.a[j--]--;
237 while (j > i)
238 t1.a[j--] += MAXN;
239 t1.a[i] += MAXN + 1 - t2.a[i];
240 }
241 else
242 t1.a[i] -= t2.a[i];
243 }
244 t1.len = big;
245 while (t1.a[t1.len - 1] == 0 && t1.len > 1) {
246 t1.len--;
247 big--;
248 }
249 if (flag)
250 t1.a[big - 1] = 0 - t1.a[big - 1];
251 return t1;
252 }
253
254 BigNum BigNum::operator * (const BigNum& b) const //两个大数之间的相乘运算
255 {
256 BigNum ret;
257 int i, j, up;
258 int temp, temp1;
259 for (i = 0; i < len; i++) {
260 up = 0;
261 for (j = 0; j < b.len; j++) {
262 temp = a[i] * b.a[j] + ret.a[i + j] + up;
263 if (temp > MAXN) {
264 temp1 = temp - temp / (MAXN + 1) * (MAXN + 1);
265 up = temp / (MAXN + 1);
266 ret.a[i + j] = temp1;
267 }
268 else {
269 up = 0;
270 ret.a[i + j] = temp;
271 }
272 }
273 if (up != 0) ret.a[i + j] = up;
274 }
275 ret.len = i + j;
276 while (ret.a[ret.len - 1] == 0 && ret.len > 1)
277 ret.len--;
278 return ret;
279 }
280 template<typename T> BigNum BigNum::operator / (const T& b) const
281 {
282 BigNum ret;
283 T i, down = 0;
284 for (i = len - 1; i >= 0; i--) {
285 ret.a[i] = (a[i] + down * (MAXN + 1)) / b;
286 down = a[i] + down * (MAXN + 1) - ret.a[i] * b;
287 }
288 ret.len = len;
289 while (ret.a[ret.len - 1] == 0 && ret.len > 1)
290 ret.len--;
291 return ret;
292 }
293 template<typename T> T BigNum::operator % (const T& b) const
294 {
295 T i, d = 0;
296 for (i = len - 1; i >= 0; i--) {
297 d = ((d * (MAXN + 1)) % b + a[i]) % b;
298 }
299 return d;
300 }
301
302
303 template<typename T> BigNum BigNum::operator^(const T& n) const //大数的n次方运算
304 {
305 BigNum t, ret(1);
306 int i;
307 if (n < 0) return 0;
308 if (n == 0)
309 return 1;
310 if (n == 1)
311 return *this;
312 int m = n;
313 while (m > 1) {
314 t = *this;
315 for (i = 1; (i << 1) <= m; i <<= 1)
316 t = t * t;
317 m -= i;
318 ret = ret * t;
319 if (m == 1) ret = ret * (*this);
320 }
321 return ret;
322 }
323
324 bool BigNum::operator > (const BigNum& b) const //大数和另一个大数的大小比较
325 {
326 int tot;
327 if (len > b.len)
328 return true;
329 else if (len == b.len) {
330 tot = len - 1;
331 while (a[tot] == b.a[tot] && tot >= 0)
332 tot--;
333 if (tot >= 0 && a[tot] > b.a[tot])
334 return true;
335 else
336 return false;
337 }
338 else
339 return false;
340 }
341
342 bool BigNum::operator < (const BigNum& b) const
343 {
344 int tot;
345 if (len > b.len)
346 return false;
347 else if (len == b.len) {
348 tot = len - 1;
349 while (a[tot] == b.a[tot] && tot >= 0)
350 tot--;
351 if (tot >= 0 && a[tot] > b.a[tot])
352 return false;
353 else
354 return false;
355 }
356 else
357 return true;
358 }
359
360 bool BigNum::operator == (const BigNum& b) const
361 {
362 int tot = len - 1;
363 if (len != b.len)
364 return false;
365 while (a[tot] == b.a[tot] && tot >= 0)
366 tot--;
367 if (tot < 0)
368 return true;
369 return false;
370 }
371 int n;
372 void BigNum::print() //输出大数
373 {
374 int i;
375 if (len >= n) {
376 cout << a[len - 1];
377 for (i = len - 2; i >= len - n; i--) {
378 cout.width(DLEN);
379 cout.fill('0');
380 cout << a[i];
381 }
382 cout << endl;
383 }
384 else {
385 cout << a[len - 1];
386 for (i = len - 2; i >= 0; i--) {
387 cout.width(DLEN);
388 cout.fill('0');
389 cout << a[i];
390 }
391 cout << endl;
392 }
393 }
394 int BigNum::Size()
395 {
396 int t = a[len - 1], cnt = 0;
397 while (t) { t /= 10; cnt++; }
398 cnt += (len - 1) * 4;
399 return cnt;
400 }
401 int BigNum::the_first()
402 {
403 int t = a[len - 1];
404 while (t > 10) { t /= 10; }
405 return t;
406 }
407 int BigNum::the_last()
408 {
409 int t = a[0];
410 return t % 10;
411 }
412 int BigNum::to_int()
413 {
414 int i, num;
415 num = a[len - 1];
416 for (i = len - 2; i >= 0; i--)
417 num = num * (MAXN + 1) + a[i];
418 return num;
419 }
420 long long int BigNum::to_long()
421 {
422 int i;
423 long long int num;
424 num = a[len - 1];
425 for (i = len - 2; i >= 0; i--)
426 num = num * (MAXN + 1) + a[i];
427 return num;
428 }
429 string BigNum::to_String()
430 {
431 int i;
432 string s = "", tp = "";
433 s += to_string(a[len - 1]);
434 for (i = len - 2; i >= 0; i--) {
435 tp = to_string(a[i]);
436 int tot = tp.size();
437 tp.insert(tp.begin(), 4 - tot, '0');
438 s = s + tp;
439 }
440 return s;
441 }
View Code
ac代码
1 #include<iostream>
2 #include<cstring>
3 #include<string>
4 #include<cstdio>
5 #include<algorithm>
6
7 using namespace std;
8 #define maxn 100100
9 #define MAXN 9999
10 #define MAXSIZE 500 //最大长度
11 #define DLEN 4
12
13 class BigNum {
14 private:
15 int a[21000]; //控制大数的位数
16 int len; //长度
17 public:
18 BigNum() { len = 1; memset(a, 0, sizeof(a)); } //构造函数
19 void XD();
20 BigNum(const int);
21 BigNum(const long long int);
22 BigNum(const char*);
23 BigNum(const string&);
24 BigNum(const BigNum&); //拷贝构造函数
25 BigNum& operator = (const BigNum&); //重载赋值运算符
26 BigNum& operator = (const int&);
27 BigNum& operator = (const long long int&);
28
29 friend istream& operator >> (istream&, BigNum&); //重载输入运算符
30 friend ostream& operator << (ostream&, BigNum&); //重载输出运算符
31
32 template<typename T> BigNum operator << (const T&) const;
33 template<typename T> BigNum operator >> (const T&) const;
34
35 BigNum operator + (const BigNum&) const; //重载加法运算符，大数加大数
36 BigNum operator - (const BigNum&) const; //重载减法运算符，大数减大数
37 BigNum operator * (const BigNum&) const; //重载乘法运算符，大数乘大数
38 bool operator > (const BigNum& b)const; //重载大于
39 bool operator < (const BigNum& b) const; //重载小于
40 bool operator == (const BigNum& b) const; //重载等于符号
41 template<typename T> BigNum operator / (const T&) const; //重载除法运算符，大数除整数
42 template<typename T> BigNum operator ^ (const T&) const; //大数的n次方
43 template<typename T> T operator % (const T&) const; //大数对int取模
44
45 template<typename T> BigNum operator + (const T& b) const { BigNum t = b; t = *this + t; return t; }
46 template<typename T> BigNum operator - (const T& b) const { BigNum t = b; t = *this - t; return t; }
47 template<typename T> BigNum operator * (const T& b) const { BigNum t = b; t = (*this) * t; return t; }
48 template<typename T> bool operator < (const T& b) const { BigNum t = b; return ((*this) < t); }
49 template<typename T> bool operator > (const T& b) const { BigNum t = b; return ((*this) > t); }
50 template<typename T> bool operator == (const T& b) const { BigNum t = b; return ((*this) == t); }
51
52 bool operator <= (const BigNum& b) const { return (*this) < b || (*this) == b; }
53 bool operator >= (const BigNum& b) const { return (*this) > b || (*this) == b; }
54 bool operator != (const BigNum& b) const { return !((*this) == b); }
55
56 template<typename T> bool operator >= (const T& b) const { BigNum t = b; return !((*this) < t); }
57 template<typename T> bool operator <= (const T& b) const { BigNum t = b; return !((*this) > t); }
58 template<typename T> bool operator != (const T& b) const { BigNum t = b; return !((*this) == t); }
59
60 BigNum& operator += (const BigNum& b) { *this = *this + b; return *this; }
61 BigNum& operator -= (const BigNum& b) { *this = *this - b; return *this; }
62 BigNum& operator *= (const BigNum& b) { *this = *this * b; return *this; }
63 template<typename T> BigNum& operator /= (const T& b) { *this = *this / b; return *this; }
64 template<typename T> BigNum& operator %= (const T& b) { *this = *this % b; return *this; }
65 template<typename T> BigNum& operator += (const T& b) { *this = *this + b; return *this; }
66 template<typename T> BigNum& operator -= (const T& b) { *this = *this - b; return *this; }
67 template<typename T> BigNum& operator *= (const T& b) { *this = *this * b; return *this; }
68 template<typename T> BigNum& operator ^= (const T& b) { *this = *this ^ b; return *this; }
69
70 BigNum operator ++ (int) { BigNum t = *this; *this += 1; return t; }
71 BigNum operator -- (int) { BigNum t = *this; *this -= 1; return t; }
72 BigNum& operator -- () { *this -= 1; return *this; }
73 BigNum& operator ++ () { *this += 1; return *this; }
74
75 template<typename T> BigNum& operator <<= (const T& b) { *this = *this << b; return *this; }
76 template<typename T> BigNum& operator >>= (const T& b) { *this = *this >> b; return *this; }
77
78 template<typename T> BigNum friend operator + (const T& a, const BigNum& b) { BigNum t = a; t = t + a; return t; }
79 template<typename T> BigNum friend operator - (const T& a, const BigNum& b) { BigNum t = a; t = t - b; return t; }
80 template<typename T> BigNum friend operator * (const T& a, const BigNum& b) { BigNum t = a; t = t * b; return t; }
81 template<typename T> friend bool operator < (const T& a, const BigNum& b) { return b > a; }
82 template<typename T> friend bool operator > (const T& a, const BigNum& b) { return b < a; }
83 template<typename T> friend bool operator <= (const T& a, const BigNum& b) { return b >= a; }
84 template<typename T> friend bool operator >= (const T& a, const BigNum& b) { return b <= a; }
85 template<typename T> friend bool operator == (const T& a, const BigNum& b) { return b == a; }
86 template<typename T> friend bool operator != (const T& a, const BigNum& b) { return b != a; }
87
88 void print(); //输出大数
89 int Size(); //返回大数长度
90 int the_first(); //返回第一个数字
91 int the_last(); //返回最后一位数字
92 int to_int(); //转化为整数
93 long long int to_long();
94 string to_String(); //转化为string类型
95 //char* to_char();
96 };
97
98 BigNum::BigNum(const int b) //将一个int类型的变量转化为大数
99 {
100 int c, d = b;
101 len = 0;
102 memset(a, 0, sizeof(a));
103 while (d > MAXN) {
104 c = d - (d / (MAXN + 1)) * (MAXN + 1);
105 d = d / (MAXN + 1);
106 a[len++] = c;
107 }
108 a[len++] = d;
109 }
110 BigNum::BigNum(const long long int b)
111 {
112 long long int c, d = b;
113 len = 0;
114 memset(a, 0, sizeof(a));
115 while (d > MAXN) {
116 c = d - (d / (MAXN + 1)) * (MAXN + 1);
117 d = d / (MAXN + 1);
118 a[len++] = c;
119 }
120 a[len++] = d;
121 }
122 BigNum::BigNum(const string& s)
123 {
124 int t, k, index, l, i;
125 memset(a, 0, sizeof(a));
126 l = s.size();
127 len = l / DLEN;
128 if (l % DLEN)
129 len++;
130 index = 0;
131 for (i = l - 1; i >= 0; i -= DLEN) {
132 t = 0;
133 k = i - DLEN + 1;
134 if (k < 0) k = 0;
135 for (int j = k; j <= i; j++)
136 t = t * 10 + s[j] - '0';
137 a[index++] = t;
138 }
139 }
140 BigNum::BigNum(const char* s) //将一个字符串类型的变量转化为大数
141 {
142 int t, k, index, l, i;
143 memset(a, 0, sizeof(a));
144 l = strlen(s);
145 len = l / DLEN;
146 if (l % DLEN)
147 len++;
148 index = 0;
149 for (i = l - 1; i >= 0; i -= DLEN) {
150 t = 0;
151 k = i - DLEN + 1;
152 if (k < 0) k = 0;
153 for (int j = k; j <= i; j++)
154 t = t * 10 + s[j] - '0';
155 a[index++] = t;
156 }
157 }
158 BigNum::BigNum(const BigNum& b) : len(b.len) //拷贝构造函数
159 {
160 memset(a, 0, sizeof(a));
161 for (int i = 0; i < len; i++)
162 a[i] = b.a[i];
163 }
164 BigNum& BigNum::operator = (const BigNum& n) //重载赋值运算符，大数之间进行赋值运算
165 {
166 len = n.len;
167 memset(a, 0, sizeof(a));
168 for (int i = 0; i < len; i++)
169 a[i] = n.a[i];
170 return *this;
171 }
172 BigNum& BigNum::operator = (const int& num)
173 {
174 BigNum t(num);
175 *this = t;
176 return *this;
177 }
178 BigNum& BigNum::operator = (const long long int& num)
179 {
180 BigNum t(num);
181 *this = t;
182 return *this;
183 }
184 void XD()
185 {
186 cout << "A hidden egg! Good luck for u!" << endl;
187 }
188
189 template<typename T> BigNum BigNum::operator << (const T& b) const
190 {
191 T temp = 1;
192 for (int i = 0; i < b; i++)
193 temp *= 2;
194 BigNum t = (*this) * temp;
195 return t;
196 }
197 template<typename T> BigNum BigNum::operator >> (const T& b) const
198 {
199 T temp = 1;
200 for (int i = 0; i < b; i++)
201 temp *= 2;
202 BigNum t = (*this) / temp;
203 return t;
204 }
205
206 BigNum BigNum::operator + (const BigNum& b) const //两个大数之间的相加运算
207 {
208 BigNum t(*this);
209 int i, big;
210 big = b.len > len ? b.len : len;
211 for (i = 0; i < big; i++) {
212 t.a[i] += b.a[i];
213 if (t.a[i] > MAXN) {
214 t.a[i + 1]++;
215 t.a[i] -= MAXN + 1;
216 }
217 }
218 if (t.a[big] != 0)
219 t.len = big + 1;
220 else
221 t.len = big;
222 return t;
223 }
224 BigNum BigNum::operator - (const BigNum& b) const //两个大数之间的相减运算
225 {
226 int i, j, big;
227 bool flag;
228 BigNum t1, t2;
229 if (*this > b) {
230 t1 = *this;
231 t2 = b;
232 flag = 0;
233 }
234 else {
235 t1 = b;
236 t2 = *this;
237 flag = 1;
238 }
239 big = t1.len;
240 for (i = 0; i < big; i++) {
241 if (t1.a[i] < t2.a[i]) {
242 j = i + 1;
243 while (t1.a[j] == 0)
244 j++;
245 t1.a[j--]--;
246 while (j > i)
247 t1.a[j--] += MAXN;
248 t1.a[i] += MAXN + 1 - t2.a[i];
249 }
250 else
251 t1.a[i] -= t2.a[i];
252 }
253 t1.len = big;
254 while (t1.a[t1.len - 1] == 0 && t1.len > 1) {
255 t1.len--;
256 big--;
257 }
258 if (flag)
259 t1.a[big - 1] = 0 - t1.a[big - 1];
260 return t1;
261 }
262
263 BigNum BigNum::operator * (const BigNum& b) const //两个大数之间的相乘运算
264 {
265 BigNum ret;
266 int i, j, up;
267 int temp, temp1;
268 for (i = 0; i < len; i++) {
269 up = 0;
270 for (j = 0; j < b.len; j++) {
271 temp = a[i] * b.a[j] + ret.a[i + j] + up;
272 if (temp > MAXN) {
273 temp1 = temp - temp / (MAXN + 1) * (MAXN + 1);
274 up = temp / (MAXN + 1);
275 ret.a[i + j] = temp1;
276 }
277 else {
278 up = 0;
279 ret.a[i + j] = temp;
280 }
281 }
282 if (up != 0) ret.a[i + j] = up;
283 }
284 ret.len = i + j;
285 while (ret.a[ret.len - 1] == 0 && ret.len > 1)
286 ret.len--;
287 return ret;
288 }
289 template<typename T> BigNum BigNum::operator / (const T& b) const
290 {
291 BigNum ret;
292 T i, down = 0;
293 for (i = len - 1; i >= 0; i--) {
294 ret.a[i] = (a[i] + down * (MAXN + 1)) / b;
295 down = a[i] + down * (MAXN + 1) - ret.a[i] * b;
296 }
297 ret.len = len;
298 while (ret.a[ret.len - 1] == 0 && ret.len > 1)
299 ret.len--;
300 return ret;
301 }
302 template<typename T> T BigNum::operator % (const T& b) const
303 {
304 T i, d = 0;
305 for (i = len - 1; i >= 0; i--) {
306 d = ((d * (MAXN + 1)) % b + a[i]) % b;
307 }
308 return d;
309 }
310
311
312 template<typename T> BigNum BigNum::operator^(const T& n) const //大数的n次方运算
313 {
314 BigNum t, ret(1);
315 int i;
316 if (n < 0) return 0;
317 if (n == 0)
318 return 1;
319 if (n == 1)
320 return *this;
321 int m = n;
322 while (m > 1) {
323 t = *this;
324 for (i = 1; (i << 1) <= m; i <<= 1)
325 t = t * t;
326 m -= i;
327 ret = ret * t;
328 if (m == 1) ret = ret * (*this);
329 }
330 return ret;
331 }
332
333 bool BigNum::operator > (const BigNum& b) const //大数和另一个大数的大小比较
334 {
335 int tot;
336 if (len > b.len)
337 return true;
338 else if (len == b.len) {
339 tot = len - 1;
340 while (a[tot] == b.a[tot] && tot >= 0)
341 tot--;
342 if (tot >= 0 && a[tot] > b.a[tot])
343 return true;
344 else
345 return false;
346 }
347 else
348 return false;
349 }
350
351 bool BigNum::operator < (const BigNum& b) const
352 {
353 int tot;
354 if (len > b.len)
355 return false;
356 else if (len == b.len) {
357 tot = len - 1;
358 while (a[tot] == b.a[tot] && tot >= 0)
359 tot--;
360 if (tot >= 0 && a[tot] > b.a[tot])
361 return false;
362 else
363 return false;
364 }
365 else
366 return true;
367 }
368
369 bool BigNum::operator == (const BigNum& b) const
370 {
371 int tot = len - 1;
372 if (len != b.len)
373 return false;
374 while (a[tot] == b.a[tot] && tot >= 0)
375 tot--;
376 if (tot < 0)
377 return true;
378 return false;
379 }
380
381 int n; //定义n
382
383 void BigNum::print() //输出大数
384 {
385 int i;
386 if (len >= n) {
387 cout << a[len - 1];
388 for (i = len - 2; i >= len - n; i--) {
389 cout.width(DLEN);
390 cout.fill('0');
391 cout << a[i];
392 }
393 cout << endl;
394 }
395 else {
396 cout << a[len - 1];
397 for (i = len - 2; i >= 0; i--) {
398 cout.width(DLEN);
399 cout.fill('0');
400 cout << a[i];
401 }
402 cout << endl;
403 }
404 }
405 int BigNum::Size()
406 {
407 int t = a[len - 1], cnt = 0;
408 while (t) { t /= 10; cnt++; }
409 cnt += (len - 1) * 4;
410 return cnt;
411 }
412 int BigNum::the_first()
413 {
414 int t = a[len - 1];
415 while (t > 10) { t /= 10; }
416 return t;
417 }
418 int BigNum::the_last()
419 {
420 int t = a[0];
421 return t % 10;
422 }
423 int BigNum::to_int()
424 {
425 int i, num;
426 num = a[len - 1];
427 for (i = len - 2; i >= 0; i--)
428 num = num * (MAXN + 1) + a[i];
429 return num;
430 }
431 long long int BigNum::to_long()
432 {
433 int i;
434 long long int num;
435 num = a[len - 1];
436 for (i = len - 2; i >= 0; i--)
437 num = num * (MAXN + 1) + a[i];
438 return num;
439 }
440 string BigNum::to_String()
441 {
442 int i;
443 string s = "", tp = "";
444 s += to_string(a[len - 1]);
445 for (i = len - 2; i >= 0; i--) {
446 tp = to_string(a[i]);
447 int tot = tp.size();
448 tp.insert(tp.begin(), 4 - tot, '0');
449 s = s + tp;
450 }
451 return s;
452 }
453
454 int p[maxn];
455 int to[maxn];
456 int vis[maxn];
457
458 int gcd1(int x, int y) {
459 return y ? gcd1(y, x % y) : x;
460 }
461 int gcd(BigNum x, int y) {
462 return gcd1(y, x % y);
463 }
464
465 BigNum lcm(BigNum ans, int res) {
466 return ans / gcd(ans, res) * res;
467 }
468
469 int main() {
470 cin >> n;
471 for (int i = 1; i <= n; i++) {
472 scanf("%d", &p[i]);
473 to[i] = p[i];
474 }
475
476 BigNum ans = BigNum(1);
477 for (int i = 1; i <= n; i++) { //找环的长度
478 if (vis[i]) continue;
479 int tmp = i;
480 int res = 0; //环的长度
481 while (to[tmp] != i) {
482 vis[tmp] = 1;
483 tmp = to[tmp];
484 res++;
485 }
486 res++;
487 ans = lcm(ans, res);
488 }
489 ans.print();
490 return 0;
491 }
View Code
参考链接：https://www.cnblogs.com/kangkang-/p/13387908.html