POJ 3258 River Hopscotch

[code]#include<stdio.h>
#include<algorithm>
using namespace std;
int  main()
{
    int l,n,m;
    int distance[50010];
    scanf("%d%d%d",&l,&n,&m);
    int i;
    for(i=1;i<=n;i++)
        scanf("%d",distance+i);
    int left=0;
    int right=l;
    int mid;
    int ans;
    sort(distance+1,distance+1+n);
    while(left<=right)
    {
        int count=0;
        int z=0;
        mid=(left+right)/2;
        for(i=1;i<=n;i++)
        {
            if(distance[i]-z>=mid)
            {
                z=distance[i];
            }
            else
            {
                count++;
            }
        }
        if(count>m)
            {
                right=mid-1;
            }
        else
            {
                ans=mid;
                left=mid+1;
            }
    }
    printf("%d\n",ans);
    return 0;
}