Create 852. Peak Index in a Mountain Array.java

Author: SharmaTushar1

java/852. Peak Index in a Mountain Array.java

@@ -0,0 +1,18 @@
+//Use binary search
+class Solution {
+    public int peakIndexInMountainArray(int[] arr) {
+        int start = 0;
+        int end = arr.length;
+        int n = arr.length;
+        while (start<=end) {
+            int mid = start+(end-start)/2;
+            if (mid!=0 && mid!=n-1 && arr[mid-1]<arr[mid] && arr[mid+1]<arr[mid]) 
+                return mid;
+            else if (mid!=n-1 && arr[mid+1]>arr[mid])
+                start = mid+1;
+            else if (mid!=0 && arr[mid-1]>arr[mid]) 
+                end = mid-1;
+        }
+        return end;
+    }
+}