[luoguP1316] 丢瓶盖（二分答案）

传送门

二分答案再判断即可

——代码

#include <cstdio>
#include <iostream>
#include <algorithm>
#define max(x, y) ((x) > (y) ? (x) : (y))
#define N 1000001

int n, m, ans, maxn;
int a[N];

inline int read()
{
    int x = 0, f = 1;
    char ch = getchar();
    for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -1;
    for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - '0';
    return x * f;
}

inline bool check(int x)
{
    int i, now = 1, sum = 1;
    for(i = 1; i <= n; i++)
        if(a[i] - a[now] >= x)
        {
            sum++;
            now = i;
        }
    return sum >= m;
}

int main()
{
    int i, j, x, y, mid;
    n = read();
    m = read();
    for(i = 1; i <= n; i++) a[i] = read(), maxn = max(a[i], maxn);
    std::sort(a + 1, a + n + 1);
    x = 1, y = maxn;
    while(x <= y)
    {
        mid = (x + y) >> 1;
        if(check(mid)) ans = mid, x = mid + 1;
        else y = mid - 1;
    }
    printf("%d
", ans);
    return 0;
}