add: 和可被K整除的子数组

README.md

@@ -353,6 +353,10 @@ LeetCode 与 LintCode 解题记录。此为个人练习仓库，代码中对重
   - LeetCode 287. 寻找重复数 <https://leetcode-cn.com/problems/find-the-duplicate-number/>
   - LintCode 633. 寻找重复的数 <https://www.lintcode.com/problem/find-the-duplicate-number/description>
 
+- [和可被K整除的子数组](src/array/subarray-sums-divisible-by-k.js)
+
+  - LeetCode 974. 和可被 K 整除的子数组 <https://leetcode-cn.com/problems/subarray-sums-divisible-by-k/>
+
 ## 栈
 
 - [最大矩阵](src/stack/maximal-rectangle.js)

src/array/subarray-sums-divisible-by-k.js

@@ -0,0 +1,17 @@
+/**
+ * @param {number[]} A
+ * @param {number} K
+ * @return {number}
+ */
+export const subarraysDivByK = function (A, K) {
+  const map = new Map([[0, 1]]); let sum = 0; let count = 0
+
+  A.forEach(n => {
+    sum = (sum + n) % K; sum = sum < 0 ? sum + K : sum
+    const temp = map.get(sum) || 0
+    count += temp
+    map.set(sum, temp + 1)
+  })
+
+  return count
+}

test/array/subarray-sums-divisible-by-k.test.js

@@ -0,0 +1,5 @@
+import { subarraysDivByK } from '../../src/array/subarray-sums-divisible-by-k'
+
+test('和可被K整除的子数组', () => {
+  expect(subarraysDivByK([4, 5, 0, -2, -3, 1], 5)).toBe(7)
+})