✨ Find Peak Element

README.md

@@ -139,3 +139,4 @@ npm run test
 | 115 |                 [FindAllDuplicatesInAnArray](src/findAllDuplicatesInAnArray/index.ts)                 |         [:green_book:](src/findAllDuplicatesInAnArray/README.md)         |    Easy    | [LeetCode](https://leetcode.com/problems/find-all-duplicates-in-an-array)                   | Array                     |
 | 116 |            [FindMinimumInRotatedSortedArray](src/findMinimumInRotatedSortedArray/index.ts)            |      [:green_book:](src/findMinimumInRotatedSortedArray/README.md)       |    Easy    | [LeetCode](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array)              | Array                     |
 | 117 |           [FindMinimumInRotatedSortedArray2](src/findMinimumInRotatedSortedArray2/index.ts)           |      [:green_book:](src/findMinimumInRotatedSortedArray2/README.md)      |    Easy    | [LeetCode](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii)           | Array                     |
+| 118 |                            [FindPeakElement](src/findPeakElement/index.ts)                            |              [:green_book:](src/findPeakElement/README.md)               |   Medium   | [LeetCode](https://leetcode.com/problems/find-peak-element)                                 | Array                     |

src/findPeakElement/README.md

@@ -0,0 +1,20 @@
+# 118.Find Peak Element
+
+## Description
+
+A peak element is an element that is greater than its neighbors.
+Given an input array where num[i] ≠ num[i+1], find a peak element and return its index.
+The array may contain multiple peaks, in that case return the index to any one of the peaks is fine.
+You may imagine that num[-1] = num[n] = -∞.
+For example, in array [1, 2, 3, 1], 3 is a peak element and your function should return the index number 2.
+
+## Example
+
+```javascript
+Input: [1, 2, 3, 1]
+Output: 2
+```
+
+## From
+
+[LeetCode](https://leetcode.com/problems/find-peak-element)

src/findPeakElement/index.ts

@@ -0,0 +1,13 @@
+export function findPeakElement(nums: number[]) {
+  let max = -Infinity
+  let position = 0
+
+  for (let i = 0; i < nums.length; i++) {
+    if (nums[i] > max) {
+      position = i
+      max = nums[i]
+    }
+  }
+
+  return position
+}

src/findPeakElement/test.ts

@@ -0,0 +1,25 @@
+import { findPeakElement } from '.'
+
+test('FindPeakElement-1', () => {
+  expect(findPeakElement([0])).toBe(0)
+})
+
+test('FindPeakElement-2', () => {
+  expect(findPeakElement([0, 1, 2])).toBe(2)
+})
+
+test('FindPeakElement-3', () => {
+  expect(findPeakElement([1, 0])).toBe(0)
+})
+
+test('FindPeakElement-4', () => {
+  expect(findPeakElement([2, 3, 4, 2, 4, 3])).toBe(2)
+})
+
+test('FindPeakElement-5', () => {
+  expect(findPeakElement([5, 0, 5])).toBe(0)
+})
+
+test('FindPeakElement-6', () => {
+  expect(findPeakElement([6, 3, 4, 6, 7, 6])).toBe(4)
+})

src/index.ts

@@ -114,3 +114,4 @@ export * from './degreeOfAnArray'
 export * from './findAllDuplicatesInAnArray'
 export * from './findMinimumInRotatedSortedArray'
 export * from './findMinimumInRotatedSortedArray2'
+export * from './findPeakElement'