solves find peak element in java

Author: anishLearnsToCode

README.md

@@ -143,7 +143,7 @@
 | 159  | 🔒 [Longest Substring With At Most Two Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters)         |                                                                                                                                                                                      |                                                                                                                                   |
 | 160  | [Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists)                                                        |                     [![Java](assets/java.png)](src/IntersectionOf2LinkedLists.java) [![Python](assets/python.png)](python/intersecction_of_two_linked_lists.py)                      |                                                                                                                                   |
 | 161  | 🔒 [One Edit Distance](https://leetcode.com/problems/one-edit-distance)                                                                                   |                                                                                                                                                                                      |                                                                                                                                   |
-| 162  | [Find Peak Element](https://leetcode.com/problems/find-peak-element)                                                                                      |                                                                                                                                                                                      |                                                                                                                                   |
+| 162  | [Find Peak Element](https://leetcode.com/problems/find-peak-element)                                                                                      |                                                                 [![Java](assets/java.png)](src/FindPeakElement.java)                                                                 |                                                                                                                                   |
 | 165  | [Compare Version Numbers](https://leetcode.com/problems/compare-version-numbers)                                                                          |                                                                                                                                                                                      |                                                                                                                                   |
 | 166  | [Fraction to Recurring Decimal](https://leetcode.com/problems/fraction-to-recurring-decimal)                                                              |                                                                                                                                                                                      |                                                                                                                                   |
 | 167  | [Two Sum II - Input Array is Sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted)                                                      |                                 [![Java](assets/java.png)](src/TwoSumIIInputArrayIsSorted.java) [![Python](assets/python.png)](python/two_sum_ii.py)                                 |                                                                                                                                   |

src/FindPeakElement.java

@@ -0,0 +1,27 @@
+// https://leetcode.com/problems/find-peak-element
+// T: O(log(N))
+// S: O(1)
+
+public class FindPeakElement {
+    public static int findPeakElement(int[] array) {
+        for (int left = 0, right = array.length - 1, middle ; left <= right ; ) {
+            middle = left + (right - left) / 2;
+
+            if (isPeakElement(array, middle)) return middle;
+
+            if (isOnIncreasingSlope(array, middle)) left = middle + 1;
+            else right = middle - 1;
+        }
+        return -1;
+    }
+
+    private static boolean isOnIncreasingSlope(int[] array, int index) {
+        return ((index > 0 && array[index - 1] < array[index]) || index == 0)
+                && ((index + 1 < array.length && array[index] < array[index + 1]) || index == array.length - 1);
+    }
+
+    private static boolean isPeakElement(int[] array, int index) {
+        return ((index > 0 && array[index - 1] < array[index]) || index == 0)
+            && ((index + 1 < array.length && array[index + 1] < array[index]) || index == array.length - 1);
+    }
+}