Added 26 solutions

Data Structures/Arrays/Left Rotation/Solution.java

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+//     Author: Rodney Shaghoulian
+//     Github: github.com/rshaghoulian
+// HackerRank: hackerrank.com/rshaghoulian
+
+import java.util.Scanner;
+
+//          Runtime: O(n)
+// Space Complexity: O(1) by doing an "in place" rotation
+public class Solution {
+
+    public static void main(String[] args) {
+        /* Read and save input */
+        Scanner scan = new Scanner(System.in);
+        int size         = scan.nextInt();
+        int numRotations = scan.nextInt();
+        int array[] = new int[size];
+        for (int i = 0; i < size; i++) {
+            array[i] = scan.nextInt();
+        }
+        scan.close();
+        
+        /* Rotate array (in place) using 3 reverse operations */
+        numRotations %= size; // to account for numRotations > size
+        int rotationSpot = size - 1 - numRotations;
+        reverse(array, 0, size - 1);
+        reverse(array, 0, rotationSpot);
+        reverse(array, rotationSpot + 1, size - 1);
+        
+        /* Print rotated array */
+        for (int i = 0; i < size; i++) {
+            System.out.print(array[i] + " ");
+        }
+    }
+    
+    /* Reverses array from "start" to "end" inclusive */
+    private static void reverse(int [] array, int start, int end) {
+        if (array == null || start < 0 || start >= array.length || 
+            end < 0 || end >= array.length || start >= end) {
+            return;
+        }
+        int mid = (start + end) / 2;
+        for (int i = start; i <= mid; i++) {
+            int offset = i - start;
+            swap(array, start + offset, end - offset);
+        }
+    }
+    
+    private static void swap(int [] array, int i, int j) {
+        int temp = array[i];
+        array[i] = array[j];
+        array[j] = temp;
+    }
+}