PAT/B/1020

这下面的代码是编译不通过的，因为其实是不用创建构造函数的，我看了liuchuo大神的代码才反应过来，直接赋值就可以了

#include <iostream>
#include <vector>
using namespace std;
class bin{
	public:
		int num;
		double price;
		double danjia;
		bin(int n1,double n2):num(n1),price(n2){
			danjia=price/num;
		}
};
bool cmp(bin a,bin b)
{
return a>b;
}
int main()
{
	int N,sum=0,p;
	int xuqiu;
	vector <int> tem(N);
	vector <bin> a(N);
	for(int i=0;i<N;++i)
	{
		cin>>tem[i];
		sum+=tem[i];
	}
	for(int i=0;i<N;++i)
	{
		cin>>p;
	 	bin t(tem[i],p);
	 	a[i]=t;
	}
	vector <int> num(sum);
	
 } 

liuchuo大神：

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
struct mooncake{
    float mount, price, unit;
};
int cmp(mooncake a, mooncake b) {
    return a.unit > b.unit;
}
int main() {
    int n, need;
    cin >> n >> need;
    vector<mooncake> a(n);
    for (int i = 0; i < n; i++) scanf("%f", &a[i].mount);
    for (int i = 0; i < n; i++) scanf("%f", &a[i].price);
    for (int i = 0; i < n; i++) a[i].unit = a[i].price / a[i].mount;
    sort(a.begin(), a.end(), cmp);
    float result = 0.0;
    for (int i = 0; i < n; i++) {
        if (a[i].mount <= need) {
            result = result + a[i].price;
        } else {
            result = result + a[i].unit * need;
            break;
        }
        need = need - a[i].mount;
    }
    printf("%.2f",result);
    return 0;
}

我最初提交的时候并没有考虑完善，虽然意识中还是只告诉自己仔细看，但还是忽视了下面的量可能是浮点数，导致只对了80%

以下是被点醒之后自己的代码：

#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>
using namespace std;
class bin{
	public:
		double num;
		double price;
		double danjia;
};
bool cmp(bin a,bin b)
{
	return a.danjia >b.danjia ;
}
int main()
{
	int N,sum=0;
	int xuqiu;
	double total=0.0;
	cin>>N>>xuqiu;
	vector <bin> a(N);
	for(int i=0;i<N;++i)
	{
		cin>>a[i].num; 
	}
	for(int i=0;i<N;++i)
	{
		cin>>a[i].price;
	}
	for(int i=0;i<N;++i) a[i].danjia=a[i].price/a[i].num;
	sort(a.begin() ,a.end(),cmp);
	for(int i=0;i<N;++i){
		if(sum+a[i].num>xuqiu) {
		total+=(xuqiu-sum)*a[i].danjia;
		break;	
	}
	sum+=a[i].num;
	total+=a[i].price;	
	}
	cout<<fixed<<setprecision(2)<<total;
	return 0;
 } 

PAT/B/1019

这道题中的Tostring 函数是我自己写的但是，不知道为什么单独使用就可以，但是放到这个文件中就不可以用了。

#include <iostream>
#include <string>
#include <algorithm>
#include <iomanip>
using namespace std;
bool cmp(char a,char b) {
	return a>b;
}
string Tostring(int n) {
	string tem;
	int t;
	for(int i=0; i<4; ++i) {
		tem.insert(tem.begin(),t%10+'0');
		t/=10;
	}
	cout<<tem<<' ';
	return tem;
}
int main() {
	string a,b;
	cin>>a;
	b=a;
	sort(a.begin(),a.end());
	sort(b.begin(),b.end(),cmp);
	int result=stoi(b)-stoi(a);
	if(result==0) {
		cout<<b<<" - "<<a<<" = 0000";
		return 0;
	}
	else cout<<b<<" - "<<a<<" = "<<setw(4)<<setfill('0')<<result<<endl;
	while(result!=6174) {
		a=Tostring(result);
		//cout<<a<<' '; 
		b=a;
		sort(a.begin(),a.end());
		sort(b.begin(),b.end(),cmp);
		result=stoi(b)-stoi(a);
		cout<<b<<" - "<<a<<" = "<<setw(4)<<setfill('0')<<result<<endl;
	}
	return 0;
}

后面凡发现是自己形参给错了，哈哈笑死，以下为改正的

#include <iostream>
#include <string>
#include <algorithm>
#include <iomanip>
using namespace std;
bool cmp(char a,char b) {
	return a>b;
}
string Tostring(int t) {
	string tem;
	for(int i=0; i<4; ++i) {
		tem.insert(tem.begin(),t%10+'0');//就是这里直接黏贴过来，形参是不一样的
		t/=10;
	}
	return tem;
}
int main() {
	string a,b;
	cin>>a;
	a.insert(0,4-a.size(),'0'); 
	b=a;
	sort(a.begin(),a.end());
	sort(b.begin(),b.end(),cmp);
	int result=stoi(b)-stoi(a);
	if(result==0) {
		cout<<b<<" - "<<a<<" = 0000";
		return 0;
	}
	else cout<<b<<" - "<<a<<" = "<<setw(4)<<setfill('0')<<result;
	while(result!=6174) {
		a=Tostring(result);
		//cout<<a<<' '; 
		b=a;
		sort(a.begin(),a.end());
		sort(b.begin(),b.end(),cmp);
		result=stoi(b)-stoi(a);cout<<endl;
		cout<<b<<" - "<<a<<" = "<<setw(4)<<setfill('0')<<result;
	}
	return 0;
}

看了以下liuchuo大神的代码，就是这么简洁高效，发现自己真是一个实足的小菜鸡，要继续努力啊

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
bool cmp(char a, char b) {return a > b;}
int main() {
    string s;
    cin >> s;
    s.insert(0, 4 - s.length(), '0');
    do {
        string a = s, b = s;
        sort(a.begin(), a.end(), cmp);
        sort(b.begin(), b.end());
        int result = stoi(a) - stoi(b);
        s = to_string(result);
        s.insert(0, 4 - s.length(), '0');
        cout << a << " - " << b << " = " << s << endl;
    } while (s != "6174" && s != "0000");
    return 0;
}