E-Aggressive cows

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
  Hint
  OUTPUT DETAILS:

FJ can put his 3 cows in the stalls at positions 1, 4 and 8, resulting in a minimum distance of 3.

Huge input data,scanf is recommended.
先进行排序，然后，进入二分判断，第i+1头要满足a[i+1]-a[i]>=x
二分找就好

#include<cstdio>#include<algorithm>#include<cstring>using namespace std;int N,C;int a[100005];int judge(int x){    int s=1;    int k=a[1];    for(int i=2;i<=N;i++)    {        if(a[i]-k>=x)        {            s++;            k=a[i];        }    }    return s;}int main(){    int i,j;    int mid;    scanf("%d%d",&N,&C);    for(i=1;i<=N;i++)    {        scanf("%d",&a[i]);    }    sort(a+1,a+1+N);    int left=0,right=a[N]-a[1];    while(left<=right)    {        mid=(left+right)/2;        if(judge(mid)>=C)            left=mid+1;        else            right=mid-1;    }    printf("%d\n",left-1);    return 0;}