Minimum difference between two elements in array

Given an array, how do we find the minimum difference between any two elements in that array?
For example consider the array [56, 18, 89, 24, 10], the minimum difference is 6 (between 18, and 24).
A straight forward method to find the minimum difference between any two pairs is to iterate through each possible pair and find the minimum difference. But this method takes O(n²) time.
This can be solved in O(n log n) time if we sort the array. Since the closest elements are always adjacent to each other in a sorted array, we can find the minimum difference in one iteration. Here is the C++ code for the same.

	#include <iostream>
	#include <vector>
	#include <algorithm>
	#include <climits>
	using namespace std;
	/* brute force algorithm */
	int min_diff1(vector<int>& arr)
	{
	int min_diff = INT_MAX;
	int i,j;
	for( i = 0; i < arr.size()-1; i++ )
	{
	for( j = i+1; j < arr.size(); j++ )
	{
	min_diff = min(min_diff, abs(arr[i]-arr[j]));
	}
	}
	return min_diff;
	}
	int min_diff(vector<int>& arr)
	{
	sort( arr.begin(), arr.end() );
	int min_diff = INT_MAX;
	for( i = 0; i < n-1; i++ )
	{
	min_diff = min(min_diff, abs(arr[i]-arr[i+1]));
	}
	return min_diff;
	}
	int main() {
	int t;
	cin >> t;
	while( t-- )
	{
	int n;
	cin >> n;
	vector<int> arr(n);
	int i;
	for( i = 0; i < n; i++ )
	{
	cin >> arr[i];
	}
	cout << min_diff(arr) << endl;
	}
	return 0;
	}

view raw mindiff_array.cpp hosted with by GitHub