题解 | 排队选人

#include <iostream>
#include <bits/stdc++.h>

using namespace std;

int main() {
    int n, k, a, b;
    cin >> n >> k >> a >> b;

 	// 记录某个同学是否满足条件
    vector<int> available(n, 1);
    for (int i = 0; i < n; ++i) {
        int num;
        cin >> num;
        available[i] = available[i] & (num >= a);
    }

    for (int i = 0; i < n; ++i) {
        int num;
        cin >> num;
        available[i] = available[i] & (num >= b);
    }
	// 计算前缀数组
    vector<int> prefixSum(n + 1, 0);
    for (int i = 0; i < n; ++i) {
        prefixSum[i + 1] = prefixSum[i] + available[i];
    }
	// 滑动窗口判断条件
    int ans = 0;
    for (int i = 0, j = k; j <= n; ++i, ++j) {
        if (prefixSum[j] - prefixSum[i] == k) {
            ++ ans;
        }
    }

    cout << ans << endl;

    return 0;
}
// 64 位输出请用 printf("%lld")