I am getting a TLE on my submission to AGGRCOW - Aggressive cows on SPOJ:
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 wants 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
t – the number of test cases, then t test cases follows.
* Line 1: Two space-separated integers: N and C
* Lines 2..N+1: Line i+1 contains an integer stall location, xiOutput
For each test case output one integer: the largest minimum distance.
Example
Input:
1 5 3 1 2 8 4 9
Output:
3
Output details:
FJ can put his 3 cows in the stalls at positions 1, 4 and 8, resulting in a minimum distance of 3.
I tried checking starting from smallest minimum distance i.e zero to the largest minimum distance that will be the solution. I used recursion to solve this question but getting TLE. How can I use binary search in this problem for making it more efficient.
#include<bits/stdc++.h>
using namespace std;
bool CanBeMin( vector<long long int> arr, unsigned int b,int s,unsigned int
cnt,long long int k){
if(cnt == b ) return true;
if(arr[s+1]=='\0') return false;
for(unsigned int i=s+1 ; arr[i]!='\0'; i++){
if (arr[i] - arr[s] > k && b-cnt <= arr.size() - i) {
cnt ++;
return CanBeMin ( arr , b , i , cnt , k);}
}
return false;}
int count ( vector <long long int> arr, unsigned int b){
long long int k=0;
while (CanBeMin ( arr , b , 0 , 0 , k)) {
k=k+1;}
return k;}
int main(){
int t;
cin >> t;
while ( t-- ){
int a , b;
cin >> a >> b;
vector<long long int> arr(a);
for( int i = 0; i < a; i++) {
cin >> arr[i];}
sort ( arr.begin(), arr.end());
if (b <= a)
cout << count (arr, b-1);
else cout<<"0";
cout << endl; }
}