区间DP UVA 10453 Make Palindrome

题目传送门

 /*
题意:问最少插入多少个字符使得字符串变成回文串
区间DP:dp[i][j]表示[l, r]的字符串要成为回文需要插入几个字符串,那么dp[l][r] = dp[l+1][r-1]; (str[l] == str[r])
dp[l][r] = min (dp[l+1][r], dp[l][r-1]) + 1,然后按照状态转移递归输出路径
*/
/************************************************
* Author :Running_Time
* Created Time :2015-8-17 14:42:57
* File Name :UVA_10453.cpp
************************************************/ #include <cstdio>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <cstdlib>
#include <ctime>
using namespace std; #define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
typedef long long ll;
const int MAXN = 1e3 + ;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + ;
char str[MAXN];
int dp[MAXN][MAXN]; void print(int l, int r) {
if (l > r) return ;
if (l == r) printf ("%c", str[l]);
else if (str[l] == str[r]) {
printf ("%c", str[l]);
print (l + , r - );
printf ("%c", str[l]);
}
else if (dp[l][r] == dp[l+][r] + ) {
printf ("%c", str[l]);
print (l + , r);
printf ("%c", str[l]);
}
else {
printf ("%c", str[r]);
print (l, r - );
printf ("%c", str[r]);
}
} void work(void) {
memset (dp, , sizeof (dp));
int len = strlen (str);
for (int i=; i<=len; ++i) {
for (int j=; j+i-<len; ++j) {
int k = j + i - ;
int &res = dp[j][k] = INF;
if (str[j] == str[k]) res = dp[j+][k-];
res = min (res, min (dp[j+][k], dp[j][k-]) + );
}
}
printf ("%d ", dp[][len-]);
print (, len - ); puts ("");
} int main(void) { //UVA 10453 Make Palindrome
while (scanf ("%s", str) == ) {
work ();
} return ;
}
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