https://nanti.jisuanke.com/t/60703

代码：

#include<bits/stdc++.h>
using namespace std;
int n, m, k, p, len;
struct song{
	int ind, v, len;
	bool like;
}a[10100], b[10100];
bool cmp(song a, song b){
	return a.v > b.v;
}
int main(){
	freopen("song.in", "r", stdin);
	freopen("song.out", "w", stdout);
	ios :: sync_with_stdio(0);
	cin >> n >> m >> k >> p;
	for(int i = 1; i <= n; i++)
		cin >> a[i].len,
		a[i].ind = i;
	for(int i = 1; i <= n; i++){
		cin >> a[i].v;
		if(a[i].v > m)
			a[i].like = 0;
        else
            a[i].like = 1;
	}
	for(int i = 1; i <= k; i++){
		int x;
		cin >> x;
		a[x].like = 0;
	}
	for(int i = 1; i <= n; i++)
		if(a[i].like)
			b[++len] = a[i];
	if(len < p || p == 0)
		cout << "aaaaaaaaa";
	else {
		sort(b + 1, b + 1 + len, cmp);
		cout << b[p].ind;
	}
	return 0;
}

得分50分，我不理解。。