Hello friends,

In this video tutorial, In this video tutorial, I have explained How To Solve Minimum Distances hackerrank problem in O(n) time.

Please watch this video till the end and let me know, If you have any doubts or a better approach to solve this problem.

If interested to know more about the generic algorithm in details-

click here for the video explanation of generic algorithm with complexity analysis.

or you can click on the image too to follow youtube tutorial.

Here is the working solution:-

source code :

static int minimumDistances(int[] a) {
		HashMap<Integer, Integer> hmap = new HashMap<>();
		int minDistance = Integer.MAX_VALUE, prevIndex = 0, currentIndex = 0;

		for (int i = 0; i < a.length; i++) {
			if (hmap.containsKey(a[i])) {
				currentIndex = i;
				prevIndex = hmap.get(a[i]);
				minDistance = Math.min((currentIndex - prevIndex), minDistance);
			}
			hmap.put(a[i], i);
		}

		return (minDistance == Integer.MAX_VALUE ? -1 : minDistance);

	}

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