add: 最大子序和

README.md

@@ -229,6 +229,12 @@ LeetCode 与 LintCode 解题记录。此为个人练习仓库，代码中对重
   - LeetCode 202. 快乐数 https://leetcode-cn.com/problems/happy-number/
   - LintCode 488. 快乐数 https://www.lintcode.com/problem/happy-number/description
 
+- [最大子序和](src/array/maximum-subarray.js)
+
+  - LeetCode 53. 最大子序和 https://leetcode-cn.com/problems/maximum-subarray/
+  - LintCode 41. 最大子数组 https://www.lintcode.com/problem/maximum-subarray/description
+  - LintCode 620. 最大子序列的和IV https://www.lintcode.com/problem/maximum-subarray-iv/description
+
 ## 栈
 
 - [最大矩阵](src/stack/maximal-rectangle.js)

src/array/maximum-subarray.js

@@ -0,0 +1,11 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+export const maxSubArray = function (nums) {
+  let max = nums[0]
+  let tmp = 0
+  nums.forEach(n => { max = Math.max(tmp > 0 ? tmp += n : tmp = n, max) })
+  // 如果当前指针所指元素之前的和小于0，则丢弃当前元素之前的数列
+  return max
+}

test/array/maximum-subarray.test.js

@@ -0,0 +1,6 @@
+import { maxSubArray } from '../../src/array/maximum-subarray'
+
+test('最大子序和', () => {
+  expect(maxSubArray([-2, 1, -3, 4, -1, 2, 1, -5, 4])).toBe(6)
+  // expect(maxSubArray([-2, 2, -3, 4, -1, 2, 1, -5, 3])).toBe(5)
+})