SPOJ - AGGRCOW

#include<bits/stdc++.h>
using namespace std;

typedef unsigned long long int  ull;
typedef long long int      ll;
typedef vector<int>        vi;
typedef vector<ll>         vll;
typedef vector<vi>         vvi;
typedef pair<int,int >     pii;
typedef vector< pii >      vpii;
typedef set<int>           sti;

#define sc                 scanf
#define pf                 printf
#define sci(n)             scanf("%d",&n)
#define scl(n)             scanf("%lld",&n)
#define scd(n)             scanf("%lf",&n)
#define scs(s)             scanf("%s",s)
#define pfi(n)             printf("%d",n)
#define pfl(n)             printf("%lld",n)
#define pff(n)             cout<<n
#define line               printf("\n")
#define spc                printf(" ")
#define loop(i,x,y)        for(int i=int(x); i<=int(y); i++)
#define rloop(i,y,x)       for(int i=int(y); i>=int(x); i--)
#define cspf(i)            printf("Case %d: ", i)
#define pb                 push_back
#define mp                 make_pair
#define ff                 first
#define ss                 second
#define all(v)             v.begin(),v.end()
#define rall(v)            v.rbegin(),v.rend()
#define read()             freopen("input.txt", "r", stdin)
#define write()            freopen("output.txt", "w", stdout)
/// Constants
#define eps                1e-9
#define PI                 acos(-1.0)  // 3.1415926535897932
#define MAX                1000009

int main()
{
    int tc;
    cin>>tc;
    while(tc--){
        int n,c;
        cin>>n>>c;
        vi vt(n);
        loop(i,0,n-1){
            cin>>vt[i];
        }
        sort(all(vt));
        int hi=vt[n-1]-vt[0];
        int lo=0;
        int k=60,ans;
        while(k--){
            int mid=(hi+lo)/2;
            int cnt=1;
            int prev=vt[0];
            loop(i,1,n-1){
                if(vt[i]-prev>=mid){
                    cnt++;
                    prev=vt[i];
                }
            }
            if(cnt<c){
                hi=mid;
            }
            else{
                lo=mid;
                ans=mid;
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}