add: 最大数和最小数

README.md

@@ -242,6 +242,10 @@ LeetCode 与 LintCode 解题记录。此为个人练习仓库，代码中对重
   - LeetCode 45. 跳跃游戏 II https://leetcode-cn.com/problems/jump-game-ii/
   - LintCode 117. 跳跃游戏 II https://www.lintcode.com/problem/jump-game-ii/description
 
+- [最大数和最小数](src/array/maximum-and-minimum.js)
+
+  LintCode 770. 最大数和最小数 https://www.lintcode.com/problem/maximum-and-minimum/description
+
 ## 栈
 
 - [最大矩阵](src/stack/maximal-rectangle.js)

src/array/maximum-and-minimum.js

@@ -0,0 +1,18 @@
+/**
+ * @param matrix: an input matrix
+ * @return: nums[0]: the maximum,nums[1]: the minimum
+ */
+export const maxAndMin = function (matrix) {
+  if (matrix[0] === undefined || matrix[0][0] === undefined) return []
+  let max = matrix[0][0]
+  let min = matrix[0][0]
+
+  for (let n = 0, len = matrix.length; n < len; n++) {
+    for (let i = 0; i < matrix[0].length; i++) {
+      max = Math.max(max, matrix[n][i])
+      min = Math.min(min, matrix[n][i])
+    }
+  }
+
+  return [max, min]
+}

test/array/maximum-and-minimum.test.js

@@ -0,0 +1,11 @@
+import { maxAndMin } from '../../src/array/maximum-and-minimum'
+
+test('最大数和最小数', () => {
+  expect(maxAndMin([
+    [1, 2, 3],
+    [4, 3, 2],
+    [6, 4, 4]
+  ])).toEqual([6, 1])
+
+  expect(maxAndMin([])).toEqual([])
+})