commit solution 202

Author: lxlxw

Diff for: index-tags.md

@@ -45,6 +45,7 @@
 |  [7](https://leetcode-cn.com/problems/reverse-integer)  |  [整数反转](/solution/1-99/0007.reverse-integer/)  |  `数学`  |  <font color=green>简单</font>  |✅ |
 |  [9](https://leetcode-cn.com/problems/palindrome-number)  |  [回文数](/solution/1-99/0009.palindrome-number/)  |  `数学`  |  <font color=green>简单</font>  |✅ |
 |  [13](https://leetcode-cn.com/problems/roman-to-integer)  |  [罗马数字转整数](/solution/1-99/0013.roman-to-integer/)  |  `数学`,`字符串`  |  <font color=green>简单</font>  |✅ |
+|  [202](https://leetcode-cn.com/problems/happy-number)  |  [快乐数](/solution/200-299/0202.happy-number/)  |  `哈希表`,`数学`  |  <font color=green>简单</font>  |✅ |
 |  [268](https://leetcode-cn.com/problems/missing-number)  |  [缺失数字](/solution/200-299/0268.missing-number/)  |  `位运算`,`数组`,`数学`  |  <font color=green>简单</font>  |✅ |
 
 #### **哈希表**
@@ -54,6 +55,7 @@
 |  [1](https://leetcode-cn.com/problems/two-sum)  |  [两数之和](/solution/1-99/0001.two-sum/)  |  `数组`,`哈希表`  |  <font color=green>简单</font>  | ✅ |
 |  [36](https://leetcode-cn.com/problems/valid-sudoku)  |  [有效的数独](/solution/1-99/0036.valid-sudoku/)  |  `哈希表`  |  <font color=blue>中等</font>  |✅ |
 |  [136](https://leetcode-cn.com/problems/single-number)  |  [只出现一次的数字](/solution/100-199/0136.single-number/)  |  `位运算`,`哈希表`  |  <font color=green>简单</font>  |✅ |
+|  [202](https://leetcode-cn.com/problems/happy-number)  |  [快乐数](/solution/200-299/0202.happy-number/)  |  `哈希表`,`数学`  |  <font color=green>简单</font>  |✅ |
 |  [217](https://leetcode-cn.com/problems/contains-duplicate)  |  [存在重复元素](/solution/200-299/0217.contains-duplicate/)  |  `数组`,`哈希表`  |  <font color=green>简单</font>  |✅ |
 |  [219](https://leetcode-cn.com/problems/contains-duplicate-ii)  |  [存在重复元素 ii](/solution/200-299/0219.contains-duplicate-ii/)  |  `数组`,`哈希表`  |  <font color=green>简单</font>  |✅ |
 

Diff for: index-type.md

@@ -64,7 +64,7 @@
 |  [196](https://leetcode-cn.com/problems/delete-duplicate-emails)  |  [删除重复的电子邮箱](/solution/100-199/0196.delete-duplicate-emails/)  |    |  <font color=green>简单</font>  |
 |  [197](https://leetcode-cn.com/problems/rising-temperature)  |  [上升的温度](/solution/100-199/0197.rising-temperature/)  |    |  <font color=green>简单</font>  |
 |  [198](https://leetcode-cn.com/problems/house-robber)  |  [打家劫舍](/solution/100-199/0198.house-robber/)  |  `动态规划`  |  <font color=green>简单</font>  |
-|  [202](https://leetcode-cn.com/problems/happy-number)  |  [快乐数](/solution/200-299/0202.happy-number/)  |  `哈希表`,`数学`  |  <font color=green>简单</font>  |
+|  [202](https://leetcode-cn.com/problems/happy-number)  |  [快乐数](/solution/200-299/0202.happy-number/)  |  `哈希表`,`数学`  |  <font color=green>简单</font>  |✅ |
 |  [203](https://leetcode-cn.com/problems/remove-linked-list-elements)  |  [移除链表元素](/solution/200-299/0203.remove-linked-list-elements/)  |  `链表`  |  <font color=green>简单</font>  |
 |  [204](https://leetcode-cn.com/problems/count-primes)  |  [计数质数](/solution/200-299/0204.count-primes/)  |  `哈希表`,`数学`  |  <font color=green>简单</font>  |
 |  [205](https://leetcode-cn.com/problems/isomorphic-strings)  |  [同构字符串](/solution/200-299/0205.isomorphic-strings/)  |  `哈希表`  |  <font color=green>简单</font>  |

Diff for: solution/200-299/0202.happy-number/README.md

@@ -0,0 +1,57 @@
+# [202. 快乐数](https://leetcode-cn.com/problems/happy-number/description/)
+
+### 题目描述
+
+<p>编写一个算法来判断一个数 <code>n</code> 是不是快乐数。</p>
+
+<p>「快乐数」定义为：对于一个正整数，每一次将该数替换为它每个位置上的数字的平方和，然后重复这个过程直到这个数变为 1，也可能是 <strong>无限循环</strong> 但始终变不到 1。如果 <strong>可以变为</strong>&nbsp; 1，那么这个数就是快乐数。</p>
+
+<p>如果 <code>n</code> 是快乐数就返回 <code>True</code> ；不是，则返回 <code>False</code> 。</p>
+
+<p>&nbsp;</p>
+
+<p><strong>示例：</strong></p>
+
+<pre><strong>输入：</strong>19
+<strong>输出：</strong>true
+<strong>解释：
+</strong>1<sup>2</sup> + 9<sup>2</sup> = 82
+8<sup>2</sup> + 2<sup>2</sup> = 68
+6<sup>2</sup> + 8<sup>2</sup> = 100
+1<sup>2</sup> + 0<sup>2</sup> + 0<sup>2</sup> = 1
+</pre>
+
+### 解题思路
+
+1. hash table
+
+### 具体解法
+
+
+#### **Golang**
+```go
+func isHappy(n int) bool {
+	numMap := make(map[int]bool)
+	for n != 1 {
+		num := 0
+		for i := 0; i < len(strconv.Itoa(n)); i++ {
+			v := n / powerf(10, i) % 10
+			num += v * v
+		}
+		n = num
+		if _, ok := numMap[n]; ok {
+			return false
+		}
+		numMap[n] = true
+	}
+	return true
+}
+
+func powerf(x int, n int) int {
+	if n == 0 {
+		return 1
+	}
+	return x * powerf(x, n-1)
+}
+```
+

Diff for: solution/200-299/0202.happy-number/solution.go

@@ -0,0 +1,38 @@
+package leetcode
+
+import (
+	"strconv"
+)
+
+/*
+ * @lc app=leetcode.cn id=202 lang=golang
+ *
+ * [202] 快乐数
+ */
+
+// @lc code=start
+func isHappy(n int) bool {
+	numMap := make(map[int]bool)
+	for n != 1 {
+		num := 0
+		for i := 0; i < len(strconv.Itoa(n)); i++ {
+			v := n / powerf(10, i) % 10
+			num += v * v
+		}
+		n = num
+		if _, ok := numMap[n]; ok {
+			return false
+		}
+		numMap[n] = true
+	}
+	return true
+}
+
+func powerf(x int, n int) int {
+	if n == 0 {
+		return 1
+	}
+	return x * powerf(x, n-1)
+}
+
+// @lc code=end

Diff for: solution/200-299/0202.happy-number/solution_test.go

@@ -0,0 +1,21 @@
+package leetcode
+
+import (
+	"testing"
+)
+
+func TestIsHappy(t *testing.T) {
+	var ret bool
+	var num int
+	num = 19
+	ret = true
+	if ret != isHappy(num) {
+		t.Fatalf("case fails %v\n", ret)
+	}
+
+	num = 2
+	ret = false
+	if ret != isHappy(num) {
+		t.Fatalf("case fails %v\n", ret)
+	}
+}

Diff for: solution/200-299/_sidebar.md

@@ -8,7 +8,7 @@
   - [200 - 299题](index-tags.md)
     - [200. 岛屿数量](solution/200-299/0200.number-of-islands/)
     - [201. 数字范围按位与](solution/200-299/0201.bitwise-and-of-numbers-range/)
-    - [202. 快乐数](solution/200-299/0202.happy-number/)
+    - [202. 快乐数 ✅](solution/200-299/0202.happy-number/)
     - [203. 移除链表元素](solution/200-299/0203.remove-linked-list-elements/)
     - [204. 计数质数](solution/200-299/0204.count-primes/)
     - [205. 同构字符串](solution/200-299/0205.isomorphic-strings/)