題意

求序列中長度>=len的連續子序列的中位數的最大值

題解

二分，列舉答案並檢查是否可行

除錯記錄

無

#include <cstdio>
#include <algorithm>
#define INF 0x3f3f3f3f
#define maxn 100005

using namespace std;

int n, len, a[maxn], sum[maxn];

bool check(int mid){
	sum[0] = 0;
	for (int i = 1; i <= n; i++)
		sum[i] = sum[
 
i - 1] + ((a[i] >= mid) ? 1 : -1);
	
	int Min = INF;
	for (int i = len; i <= n; i++){
		Min = min(Min, sum[i - len]);
		if (sum[i] - Min > 0) return true;
	}
	return false;
}

int main(){
	scanf("%d%d", &n, &len);
	for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
	
	int l = 1,
 
 r = INF, ans; 
	
	while (l <= r){
		int mid = (l + r) >> 1;
		if (check(mid)) l = mid + 1, ans = mid;
		else r = mid - 1;
	}
	printf("%d\n", ans);
	
	return 0;
}