C++ 代码

#include <iostream>
#include <string>
#include <queue>
#include <unordered_map>
#include <algorithm>
using namespace std;

void PrintNum(vector<int>& num) {
    for (auto& i : num) {
        printf("%d", i);
    }
}

void PrintEq(vector<int>& a, vector<int>& b, vector<int>& c) {
    PrintNum(a);
    printf(" - ");
    PrintNum(b);
    printf(" = ");
    PrintNum(c);
    printf("\n");
}

int main() {
    int n;
    cin >> n;
    vector<int> num, iNum, dNum, tmp;
    for (int i = 0; i < 4; i++) {
        num.push_back(n % 10);
        n /= 10;
    }

    int t = 0;
    int isFrist = true;
    while (true) {
        tmp = num;
        iNum = num;
        dNum = num;
        sort(iNum.begin(), iNum.end());
        sort(dNum.begin(), dNum.end(), greater<int>());

        for (int i = 3; i >= 0; i--) {
            bool flag = false;
            t = dNum[i] - iNum[i] - t;
            if (t < 0) {
                t += 10;
                flag = true;
            }
            num[i] = t % 10;
            if (flag) t = 1;
            else t = 0;
        }
        if (!isFrist && tmp == num) break;
        PrintEq(dNum, iNum, num);
        isFrist = false;
    }
    return 0;
}