From ecab5b88502f5d9cb116d9e399c105f20500d6e6 Mon Sep 17 00:00:00 2001
From: yi-ge <a@wyr.me>
Date: Thu, 30 Apr 2020 13:58:03 +0800
Subject: [PATCH] =?UTF-8?q?add:=20=E5=BF=AB=E4=B9=90=E6=95=B0?=
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Content-Type: text/plain; charset=UTF-8
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---
 README.md                       |  5 +++++
 src/array/happy-number.js       | 14 ++++++++++++++
 test/array/happy-number.test.js |  6 ++++++
 3 files changed, 25 insertions(+)
 create mode 100644 src/array/happy-number.js
 create mode 100644 test/array/happy-number.test.js

diff --git a/README.md b/README.md
index 1c47296..05ec6db 100644
--- a/README.md
+++ b/README.md
@@ -219,6 +219,11 @@ LeetCode 与 LintCode 解题记录。此为个人练习仓库，代码中对重
   - LeetCode 852. 山脉数组的峰顶索引 https://leetcode-cn.com/problems/peak-index-in-a-mountain-array/
   - LintCode 585. 山脉序列中的最大值 https://www.lintcode.com/problem/maximum-number-in-mountain-sequence/description
 
+- [快乐数](src/array/happy-number.js)
+
+  - 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
+
 ## 栈
 
 - [最大矩阵](src/stack/maximal-rectangle.js)
diff --git a/src/array/happy-number.js b/src/array/happy-number.js
new file mode 100644
index 0000000..2415b83
--- /dev/null
+++ b/src/array/happy-number.js
@@ -0,0 +1,14 @@
+/**
+ * @param {number} n
+ * @return {boolean}
+ */
+export const isHappy = function (n) {
+  const set = new Set()
+
+  while (n !== 1 && !set.has(n)) {
+    set.add(n)
+    n = n.toString().split('').reduce((a, b) => a + b * b, 0)
+  }
+
+  return n === 1
+}
diff --git a/test/array/happy-number.test.js b/test/array/happy-number.test.js
new file mode 100644
index 0000000..727ed57
--- /dev/null
+++ b/test/array/happy-number.test.js
@@ -0,0 +1,6 @@
+import { isHappy } from '../../src/array/happy-number'
+
+test('快乐数', () => {
+  expect(isHappy(19)).toBe(true)
+  expect(isHappy(5)).toBe(false)
+})