solution done

Author: Ram swaroop

src/me/ramswaroop/arrays/MaxIndexDiff.java

@@ -0,0 +1,48 @@
+package me.ramswaroop.arrays;
+
+/**
+ * Created by IntelliJ IDEA.
+ *
+ * @author: ramswaroop
+ * @date: 9/1/15
+ * @time: 10:21 PM
+ */
+public class MaxIndexDiff {
+
+    /**
+     * @param a
+     * @return
+     */
+    public static int maxDiff(int[] a) {
+        int maxDiff = -1;
+        int[] leftMin = new int[a.length], rightMax = new int[a.length];
+
+        leftMin[0] = a[0];
+        for (int i = 1; i < a.length; i++) {
+            leftMin[i] = Math.min(a[i], leftMin[i - 1]);
+        }
+
+        rightMax[a.length - 1] = a[a.length - 1];
+        for (int i = a.length - 2; i >= 0; i--) {
+            rightMax[i] = Math.max(a[i], rightMax[i + 1]);
+        }
+
+        for (int i = 0, j = 0; i < a.length && j < a.length; ) {
+            if (rightMax[j] > leftMin[i]) {
+                maxDiff = Math.max(maxDiff, j - i);
+                j++;
+            } else {
+                i++;
+            }
+        }
+        return maxDiff;
+    }
+
+    public static void main(String a[]) {
+        System.out.println(maxDiff(new int[]{34, 8, 10, 3, 2, 80, 30, 33, 1}));
+        System.out.println(maxDiff(new int[]{9, 2, 3, 4, 5, 6, 7, 8, 18, 0}));
+        System.out.println(maxDiff(new int[]{1, 2, 3, 4, 5, 6}));
+        System.out.println(maxDiff(new int[]{6, 5, 4, 3, 2, 1}));
+        System.out.println(maxDiff(new int[]{10, 11, 12, 13, 14, 6, 9, 7, 5, 3}));
+    }
+}