python/TangDou/KaoShi/比身高.cpp

#include <iostream>
using namespace std;
/**
3 0
165 175 163
155 165 157
答案：4
*/

int n, k;

const int N = 110;
int a[N], b[N];
int cnt;
int st[N];

void dfs(int u, int s) {
    if (u == n + 1) {
        cnt++;
        return;
    }
    for (int i = 1; i <= n; i++) {
        if (!st[i]) {
            if (a[u] >= b[i]) {
                st[i] = 1;
                dfs(u + 1, s);
                st[i] = 0;
            }

            if (a[u] < b[i] && s < k) {
                st[i] = 1;
                dfs(u + 1, s + 1);
                st[i] = 0;
            }
        }
    }
}
int main() {
    cin >> n >> k;
    for (int i = 1; i <= n; i++) cin >> a[i];
    for (int i = 1; i <= n; i++) cin >> b[i];
    dfs(1, 0);
    printf("%d\n", cnt);
    return 0;
}