ChocolateDistributionProblem.cpp

// C++ program to solve chocolate distribution
// problem
#include <bits/stdc++.h>
using namespace std;

// arr[0..n-1] represents sizes of packets
// m is number of students.
// Returns minimum difference between maximum
// and minimum values of distribution.
int findMinDiff(int arr[], int n, int m)
{
	// if there are no chocolates or number
	// of students is 0
	if (m == 0 || n == 0)
		return 0;

	// Sort the given packets
	sort(arr, arr + n);

	// Number of students cannot be more than
	// number of packets
	if (n < m)
		return -1;

	// Largest number of chocolates
	int min_diff = INT_MAX;

	// Find the subarray of size m such that
	// difference between last (maximum in case
	// of sorted) and first (minimum in case of
	// sorted) elements of subarray is minimum.

	for (int i = 0; i + m - 1 < n; i++) {
		int diff = arr[i + m - 1] - arr[i];
		if (diff < min_diff)
			min_diff = diff;
	}
	return min_diff;
}

int main()
{
	int arr[] = { 12, 4, 7, 9, 2, 23, 25, 41, 30,
				40, 28, 42, 30, 44, 48, 43, 50 };
	int m = 7; // Number of students
	int n = sizeof(arr) / sizeof(arr[0]);
	cout << "Minimum difference is "
		<< findMinDiff(arr, n, m);
	return 0;
}


gfg solution 
//{ Driver Code Starts
#include <bits/stdc++.h>
using namespace std;

// } Driver Code Ends

class Solution {
public:

long long findMinDiff(vector<long long> a, long long n, long long m){
    //code
        long long mindiff=INT_MAX;
        sort(a.begin(),a.end());
        long long i=0;
        long long j=m-1;
        while(j<n){
            mindiff=min(mindiff,a[j++]-a[i++]);
        }
        return mindiff;
    
    }
};
 

//{ Driver Code Starts.
int main() {
	long long t;
	cin>>t;
	while(t--)
	{
		long long n;
		cin>>n;
		vector<long long> a;
		long long x;
		for(long long i=0;i<n;i++)
		{
			cin>>x;
			a.push_back(x);
		}
		
		long long m;
		cin>>m;
		Solution ob;
		cout<<ob.findMinDiff(a,n,m)<<endl;
	}
	return 0;
}
// } Driver Code Ends