POJ - 2456 Aggressive cows

Subsequence
Time limit 1000 ms Memory limit 65536 kB
Description
Farmer John has built a new long barn, with N (2 <= N <= 100,000) stalls. The stalls are located along a straight line at positions x1,…,xN (0 <= xi <= 1,000,000,000).

His C (2 <= C <= N) cows don’t like this barn layout and become aggressive towards each other once put into a stall. To prevent the cows from hurting each other, FJ want to assign the cows to the stalls, such that the minimum distance between any two of them is as large as possible. What is the largest minimum distance?
Input
* Line 1: Two space-separated integers: N and C
* Lines 2..N+1: Line i+1 contains an integer stall location, xi

Output
* Line 1: One integer: the largest minimum distance

Sample Input
5 3
1
2
8
4
9

Sample Output
3

题目大意：给你n个点代表牛圈的位置，然后m只牛，让你尽量将牛分开使他们的距离最远。

解法：二分呀(●´ω｀●)φ

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int n,m;
int a[100005];
bool search(int d)
{
    int last=0;
    for(int i=1;i<m;i++)
    {
        int front=last+1;
        while(front<n&&a[front]-a[last]<d)
            front++;
        if(front==n)
            return false;
        last=front;
    }
    return true;
}

void solve()
{
    for(int i=0;i<n;i++)
        scanf("%d",&a[i]);
    //cout<<a[0];
    sort(a,a+n);
    int l=0;
    int r=1e5+5;
    while(r-l>1)
    {
        int mid=(l+r)/2;
        if(search(mid))
            l=mid;
        else
            r=mid;
    }
    printf("%d\n",l);
}
int main()
{
    scanf("%d%d",&n,&m);
    solve();
}