Gym 101510C-Computer Science

传送门

二分，正反都扫一遍不连续K个不符条件即可

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define INF 0x3f3f3f3f3f3f3f3f
using namespace std;
typedef long long LL;

const int maxn = 2e5 + 10;
int A[maxn];
int ans[maxn];
int N, K;

bool ck(int x) {
    int cnt = K - 1;
    for (int i = 0; i < N + 1 - K; i++) {
        if (A[i + K - 1] - A[i] > x) {
            cnt++;
        } else {
            cnt = 0;
        }
        if (cnt == K) return false;
    }
    cnt = K - 1;
    for (int i = N - 1; i >= K - 1; i--) {
        if (A[i] - A[i - K + 1] > x) {
            cnt++;
        } else {
            cnt = 0;
        }
        if (cnt == K) return false;
    }
    return true;
}

int main() {
    scanf("%d%d", &N, &K);
    for (int i = 0; i < N; i++) {
        scanf("%d", &A[i]);
    }
    sort(A, A + N);
    int dn = 0, up = A[N - 1] - A[0] + 1;
    while (dn < up - 1) {
        int mid = (up - dn) / 2 + dn;
        if (ck(mid)) {
            up = mid;
        } else {
            dn = mid;
        }
    }
    printf("%d
", dn == 0 ? dn : up);
    return 0;
}


/*
4
2
-1 2 4 100
*/