bzoj4525: [Usaco2016 Jan]Angry Cows

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
const int maxn = 50000 + 10;

int n,k,l,r,mid,ans,d;
int a[maxn];

bool check(int dist) {
    dist=2*dist;
    int d=0,sum=1;
    for(int i=2;i<=n;i++) {
        if(a[i]-a[i-1]>dist-d) {
            sum++;
            d=0;
        }
        else d+=a[i]-a[i-1];
    }
    //printf("%d %d\n",dist/2,sum);
    return sum<=k;
}

int main() {
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++) scanf("%d",&a[i]);
    sort(a+1,a+n+1);
    l=1;r=a[n];
    while(l<r) {
        mid=(l+r)>>1;
        if(check(mid)) r=mid;
        else l=mid+1;
    }
    printf("%d\n",l);
    return 0;
}