暴力求解 0.2s

#include <iostream>
#include <algorithm>
using namespace std;

int vec[9] = {1, 2, 3, 4, 5, 6, 7, 8, 9};


int cal(int x, int y)
{
    int t = 0;
    for (int i = x; i <= y; i ++ )
        t = t * 10 + vec[i];
    return t;
}


int main()
{
    int target, a, b, c, t, cnt = 0, ans = 0;
    cin >> t;
    target = t;

    while (t)  // 求a的最大数位
    {
        cnt ++;
        t /= 10;
    }

    do 
    {
        for (int i = 0; i <= cnt - 1; i ++ )
        {
            for (int j = i + 1; j <= 7; j ++ )
            {
                a = cal(0, i);
                b = cal(i + 1, j);
                c = cal(j + 1, 8);

                if (target * c == a * c + b ) ans ++;
            }
        }

    } while (next_permutation(vec, vec + 9));

    printf("%d", ans);

    return 0;
}