[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 = , f = ;
     char ch = getchar();
     for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -;
     for(; isdigit(ch); ch = getchar()) x = (x << ) + (x << ) + ch - '';
     return x * f;
 }

 inline bool check(int x)
 {
     int i, now = , sum = ;
     for(i = ; 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 = ; i <= n; i++) a[i] = read(), maxn = max(a[i], maxn);
     std::sort(a + , a + n + );
     x = , y = maxn;
     while(x <= y)
     {
         mid = (x + y) >> ;
         if(check(mid)) ans = mid, x = mid + ;
         else y = mid - ;
     }
     printf("%d\n", ans);
     return ;
 }