pat B1019

pat B1019

题目链接如下:
添加链接描述
代码如下:

#include <iostream>
#include<string>
#include<algorithm>

using namespace std;

bool higher(int a, int b) {
	return a > b;
}
int main() {

	string s1(4, 0);
	cin >> s1;

	for (int i = 0; i < s1.size(); i++) {
		if (s1.size() < 4)
			s1.insert(0, "0");
	}
	int cnt1 = 0;
	for (int i = 1; i < s1.size(); i++) {
		if (s1[i] != s1[i - 1]) cnt1++;
	}
	if (cnt1 == 0) {
		cout << s1 << " " << "-" << " " << s1 << " " << "=" << " " << "0000" << endl;
		return 0;
	}
	int num = 0;
	while (1) {
		sort(s1.begin(), s1.end(), higher);
		string s2 = s1;
		sort(s1.begin(), s1.end());
		string s3 = s1;
		num = stoi(s2) - stoi(s3);
		s1 = to_string(num);
		for (int i = 0; i < s1.size(); i++) {
			if (s1.size() < 4)
				s1.insert(0, "0");
		}
		/* s1的长度不大,也可以一个一个在s1的第一位前插入"0",******   注意插入的是字符串   ******
		if (s1.size() == 3) s1.insert(0, "0");
		if (s1.size() == 2) s1.insert(0, "00");
		if (s1.size() == 1) s1.insert(0, "000");
		*/
		string s4 = s1;
		cout << s2 << " " << "-" << " " << s3 << " " << "=" << " " << s4 << endl;
		if (s1 == "6174") break;
	}


	system("pause");
	return 0;
}