Added 10 solutions

General Programming/Basic Programming/Minimum Distances/Solution.java

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+//     Author: Rodney Shaghoulian
+//     Github: github.com/rshaghoulian
+// HackerRank: hackerrank.com/rshaghoulian
+
+import java.util.Scanner;
+import java.util.HashMap;
+
+// Main trick: Use a HashMap<Integer, Integer> that maps from "value" to "index" 
+//             to keep track of of the largest index for each value that we've 
+//             seen so far as we loop through array
+
+//  Time Complexity: O(n)
+// Space Compleixty: O(n)
+public class Solution {
+    public static void main(String[] args) {
+        /* Save input */
+        Scanner scan = new Scanner(System.in);
+        int n = scan.nextInt();
+        int[] array = new int[n];
+        for (int i = 0; i < n; i++) {
+            array[i] = scan.nextInt();
+        }
+        scan.close();
+        
+        /* Calculate + print result */
+        System.out.println(solve(array));
+    }
+    
+    private static int solve(int[] array) {
+        HashMap<Integer, Integer> map = new HashMap<>();
+        int minDistance = Integer.MAX_VALUE;
+        for (int i = 0; i < array.length; i++) {
+            if (map.containsKey(array[i])) {
+                int prevIndex = map.get(array[i]);
+                int currDistance = i - prevIndex;
+                minDistance = Math.min(minDistance, currDistance);
+            }
+            map.put(array[i], i);
+        }
+        return minDistance == Integer.MAX_VALUE ? -1 : minDistance;
+    }
+}