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‎index-tags.md‎

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| 题号 | 题解 | 标签 | 难度 | 是否解题 |
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| --- | --- | --- | --- | --- |
3535
| [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> |✅ |
36+
| [14](https://leetcode-cn.com/problems/longest-common-prefix) | [最长公共前缀](/solution/1-99/0014.longest-common-prefix/) | `字符串` | <font color=green>简单</font> |✅ |
3637
| [20](https://leetcode-cn.com/problems/valid-parentheses) | [有效的括号](/solution/1-99/0020.valid-parentheses/) | `栈`,`字符串` | <font color=green>简单</font> |✅ |
3738
| [28](https://leetcode-cn.com/problems/implement-strstr) | [实现 strstr()](/solution/1-99/0028.implement-strstr%28%29/) | `双指针`,`字符串` | <font color=green>简单</font> |✅ |
3839
| [49](https://leetcode-cn.com/problems/group-anagrams) | [字母异位词分组](/solution/1-99/0049.group-anagrams/) | `哈希表`,`字符串` | <font color=blue>中等</font> |✅ |
@@ -51,6 +52,7 @@
5152
| [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> |✅ |
5253
| [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> |✅ |
5354
| [50](https://leetcode-cn.com/problems/powx-n) | [pow(x, n)](/solution/1-99/0050.pow%28x%2c-n%29/) | `数学`,`二分查找` | <font color=blue>中等</font> |✅ |
55+
| [69](https://leetcode-cn.com/problems/sqrtx) | [x 的平方根](/solution/1-99/0069.sqrt%28x%29/) | `数学`,`二分查找` | <font color=green>简单</font> |✅ |
5456
| [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> |✅ |
5557
| [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> |✅ |
5658
| [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> |✅ |
@@ -113,6 +115,7 @@
113115
| --- | --- | --- | --- | --- |
114116
| [35](https://leetcode-cn.com/problems/search-insert-position) | [搜索插入位置](/solution/1-99/0035.search-insert-position/) | `数组`,`二分查找` | <font color=green>简单</font> |✅ |
115117
| [50](https://leetcode-cn.com/problems/powx-n) | [pow(x, n)](/solution/1-99/0050.pow%28x%2c-n%29/) | `数学`,`二分查找` | <font color=blue>中等</font> |✅ |
118+
| [69](https://leetcode-cn.com/problems/sqrtx) | [x 的平方根](/solution/1-99/0069.sqrt%28x%29/) | `数学`,`二分查找` | <font color=green>简单</font> |✅ |
116119
| [167](https://leetcode-cn.com/problems/two-sum-ii-input-array-is-sorted) | [两数之和 ii - 输入有序数组](/solution/100-199/0167.two-sum-ii---input-array-is-sorted/) | `数组`,`双指针`,`二分查找` | <font color=green>简单</font> |✅ |
117120
| [209](https://leetcode-cn.com/problems/minimum-size-subarray-sum) | [长度最小的子数组](/solution/200-299/0209.minimum-size-subarray-sum/) | `数组`,`双指针`,`二分查找` | <font color=blue>中等</font> |✅ |
118121

‎index-type.md‎

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1111
| [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> |✅ |
1212
| [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> |✅ |
1313
| [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> |✅ |
14-
| [14](https://leetcode-cn.com/problems/longest-common-prefix) | [最长公共前缀](/solution/1-99/0014.longest-common-prefix/) | `字符串` | <font color=green>简单</font> |
14+
| [14](https://leetcode-cn.com/problems/longest-common-prefix) | [最长公共前缀](/solution/1-99/0014.longest-common-prefix/) | `字符串` | <font color=green>简单</font> |✅ |
1515
| [20](https://leetcode-cn.com/problems/valid-parentheses) | [有效的括号](/solution/1-99/0020.valid-parentheses/) | `栈`,`字符串` | <font color=green>简单</font> |✅ |
1616
| [21](https://leetcode-cn.com/problems/merge-two-sorted-lists) | [合并两个有序链表](/solution/1-99/0021.merge-two-sorted-lists/) | `链表` | <font color=green>简单</font> |✅ |
1717
| [26](https://leetcode-cn.com/problems/remove-duplicates-from-sorted-array) | [删除排序数组中的重复项](/solution/1-99/0026.remove-duplicates-from-sorted-array/) | `数组`,`双指针` | <font color=green>简单</font> |✅ |
@@ -23,7 +23,7 @@
2323
| [58](https://leetcode-cn.com/problems/length-of-last-word) | [最后一个单词的长度](/solution/1-99/0058.length-of-last-word/) | `字符串` | <font color=green>简单</font> |✅ |
2424
| [66](https://leetcode-cn.com/problems/plus-one) | [加一](/solution/1-99/0066.plus-one/) | `数组` | <font color=green>简单</font> |✅ |
2525
| [67](https://leetcode-cn.com/problems/add-binary) | [二进制求和](/solution/1-99/0067.add-binary/) | `数学`,`字符串` | <font color=green>简单</font> |
26-
| [69](https://leetcode-cn.com/problems/sqrtx) | [x 的平方根](/solution/1-99/0069.sqrt%28x%29/) | `数学`,`二分查找` | <font color=green>简单</font> |
26+
| [69](https://leetcode-cn.com/problems/sqrtx) | [x 的平方根](/solution/1-99/0069.sqrt%28x%29/) | `数学`,`二分查找` | <font color=green>简单</font> |✅ |
2727
| [70](https://leetcode-cn.com/problems/climbing-stairs) | [爬楼梯](/solution/1-99/0070.climbing-stairs/) | `动态规划` | <font color=green>简单</font> |
2828
| [83](https://leetcode-cn.com/problems/remove-duplicates-from-sorted-list) | [删除排序链表中的重复元素](/solution/1-99/0083.remove-duplicates-from-sorted-list/) | `链表` | <font color=green>简单</font> |✅ |
2929
| [88](https://leetcode-cn.com/problems/merge-sorted-array) | [合并两个有序数组](/solution/1-99/0088.merge-sorted-array/) | `数组`,`双指针` | <font color=green>简单</font> |✅ |

‎solution/1-99/0014.longest-common-prefix/README.md‎

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# [14. 最长公共前缀](https://leetcode-cn.com/problems/longest-common-prefix)
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33
### 题目描述
4-
<!-- 这里写题目描述 -->
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55
<p>编写一个函数来查找字符串数组中的最长公共前缀。</p>
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<p>如果不存在公共前缀，返回空字符串&nbsp;<code>&quot;&quot;</code>。</p>
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### 解题思路
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![](http://lc-photo.xwlin.com/14.png)
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1. 纵向扫描。纵向扫描时，从前往后遍历所有字符串的每一列，比较相同列上的字符是否相同，如果相同则继续对下一列进行比较，如果不相同则当前列不再属于公共前缀，当前列之前的部分为最长公共前缀。
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### 具体解法
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<!-- tabs:start -->
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#### **Golang**
3638
```go
37-
39+
func longestCommonPrefix(strs []string) string {
40+
if len(strs) == 0 {
41+
return ""
42+
}
43+
var res string
44+
sort.Strings(strs)
45+
for k := range strs[0] {
46+
flag := true
47+
for i := 0; i < len(strs)-1; i++ {
48+
if strs[i][k] != strs[i+1][k] {
49+
flag = false
50+
break
51+
}
52+
}
53+
if flag {
54+
res += strs[0][k : k+1]
55+
} else {
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break
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}
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}
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return res
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}
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```
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<!-- tabs:end -->
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‎solution/1-99/0014.longest-common-prefix/solution.go‎

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package leetcode
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import (
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"sort"
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)
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7+
/*
8+
* @lc app=leetcode.cn id=14 lang=golang
9+
*
10+
* [14] 最长公共前缀
11+
*/
12+
13+
// @lc code=start
14+
func longestCommonPrefix(strs []string) string {
15+
if len(strs) == 0 {
16+
return ""
17+
}
18+
var res string
19+
sort.Strings(strs)
20+
for k := range strs[0] {
21+
flag := true
22+
for i := 0; i < len(strs)-1; i++ {
23+
if strs[i][k] != strs[i+1][k] {
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flag = false
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break
26+
}
27+
}
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if flag {
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res += strs[0][k : k+1]
30+
} else {
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break
32+
}
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}
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return res
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}
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// @lc code=end

‎solution/1-99/0014.longest-common-prefix/solution_test.go‎

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package leetcode
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import (
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"testing"
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)
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func TestLongestCommonPrefix(t *testing.T) {
8+
var s []string
9+
var ret string
10+
s = []string{"flower", "flow", "flight"}
11+
ret = "fl"
12+
if ret != longestCommonPrefix(s) {
13+
t.Fatalf("case fails %v\n", ret)
14+
}
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16+
s = []string{}
17+
ret = ""
18+
if ret != longestCommonPrefix(s) {
19+
t.Fatalf("case fails %v\n", ret)
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}
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}

‎solution/1-99/0069.sqrtx/README.md‎

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# [69. x 的平方根](https://leetcode-cn.com/problems/sqrtx)
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### 题目描述
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<!-- 这里写题目描述 -->
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<p>实现&nbsp;<code>int sqrt(int x)</code>&nbsp;函数。</p>
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<p>计算并返回&nbsp;<em>x</em>&nbsp;的平方根，其中&nbsp;<em>x </em>是非负整数。</p>
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### 解题思路
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1. 二分查找
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### 具体解法
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<!-- tabs:start -->
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#### **Golang**
3535
```go
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func mySqrt(x int) int {
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if x == 1 {
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return 1
39+
}
40+
l, r := 0, x
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for {
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mid := (l + r) / 2
43+
if mid == l {
44+
return mid
45+
}
46+
sqr := mid * mid
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if sqr > x {
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r = mid
49+
}
50+
if sqr < x {
51+
l = mid
52+
}
53+
if sqr == x {
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return mid
55+
}
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}
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}
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```
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<!-- tabs:end -->
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‎solution/1-99/0069.sqrtx/solution.go‎

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package leetcode
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/*
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* @lc app=leetcode.cn id=69 lang=golang
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*
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* [69] x 的平方根
7+
*/
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9+
// @lc code=start
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func mySqrt(x int) int {
11+
if x == 1 {
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return 1
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}
14+
l, r := 0, x
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for {
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mid := (l + r) / 2
17+
if mid == l {
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return mid
19+
}
20+
sqr := mid * mid
21+
if sqr > x {
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r = mid
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}
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if sqr < x {
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l = mid
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}
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if sqr == x {
28+
return mid
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}
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}
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}
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// @lc code=end

‎solution/1-99/0069.sqrtx/solution_test.go‎

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package leetcode
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import (
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"testing"
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)
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func TestMySqrt(t *testing.T) {
8+
var x int
9+
var ret int
10+
x = 8
11+
ret = 2
12+
if ret != mySqrt(x) {
13+
t.Fatalf("case fails %v\n", ret)
14+
}
15+
16+
x = 1
17+
ret = 1
18+
if ret != mySqrt(x) {
19+
t.Fatalf("case fails %v\n", ret)
20+
}
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x = 101
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ret = 10
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if ret != mySqrt(x) {
25+
t.Fatalf("case fails %v\n", ret)
26+
}
27+
}

‎solution/1-99/_sidebar.md‎

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- [11. 盛最多水的容器 ✅](solution/1-99/0011.container-with-most-water/)
2020
- [12. 整数转罗马数字](solution/1-99/0012.integer-to-roman/)
2121
- [13. 罗马数字转整数 ✅](solution/1-99/0013.roman-to-integer/)
22-
- [14. 最长公共前缀](solution/1-99/0014.longest-common-prefix/)
22+
- [14. 最长公共前缀 ✅](solution/1-99/0014.longest-common-prefix/)
2323
- [15. 三数之和 ✅](solution/1-99/0015.3sum/)
2424
- [16. 最接近的三数之和](solution/1-99/0016.3sum-closest/)
2525
- [17. 电话号码的字母组合](solution/1-99/0017.letter-combinations-of-a-phone-number/)
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7474
- [66. 加一 ✅](solution/1-99/0066.plus-one/)
7575
- [67. 二进制求和](solution/1-99/0067.add-binary/)
7676
- [68. 文本左右对齐](solution/1-99/0068.text-justification/)
77-
- [69. x 的平方根](solution/1-99/0069.sqrtx/)
77+
- [69. x 的平方根 ✅](solution/1-99/0069.sqrtx/)
7878
- [70. 爬楼梯](solution/1-99/0070.climbing-stairs/)
7979
- [71. 简化路径](solution/1-99/0071.simplify-path/)
8080
- [72. 编辑距离](solution/1-99/0072.edit-distance/)

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