python/TangDou/Test/TestC.cpp

#include <bits/stdc++.h>

using namespace std;
int cnt;

int main() {
    int n = 10;
    int u = 1 << n;
    for (int s = 0; s <= u - 1; s++) {
        int q = 4;
        for (int i = n - 1; i >= 0; i--)
            if (s & (1 << i)) q--;
        if (!q)cnt++;
    }
    cout << cnt << endl;
    return 0;
}