POJ 2456_Aggressive cows

题意：

分析：

代码：

#include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
const int maxn = 100005, INF =0x3fffffff;
typedef long long ll;
int x[maxn];
int N, C;
int judge(int a)
{
int last = 0, cnt  = 1, tmp;
while(last < N - 1){
tmp = last + 1;
while(x[tmp] - x[last] < a) tmp++;
if(tmp < N) cnt++;
if(cnt >= C) return 1;
last = tmp ;
}
return 0;
}
int main (void)
{
scanf("%d%d",&N,&C);
for(int i = 0; i < N; i++) scanf("%d",&x[i]);
sort(x, x + N);
int l = 0, r = INF, mid;
while(l<r-1){
mid = l + (r - l)/2;
if(judge(mid)) l  = mid;
else r = mid;
}
printf("%d\n",l);
}