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feat: 34. Find First and Last Position of Element in Sorted Array
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‎Leetcode/0034.Find-First-and-Last-Position-of-Element-in-Sorted-Array/README.md

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---
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title: 0034. Find First and Last Position of Element in Sorted Array
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subtitle: "https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/description/"
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date: 2024-01-22T21:20:00+08:00
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lastmod: 2024-01-22T21:20:00+08:00
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draft: false
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author: "Kimi.Tsai"
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authorLink: "https://kimi0230.github.io/"
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description: "0034.Find-First-and-Last-Position-of-Element-in-Sorted-Array"
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license: ""
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images: []
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tags: [LeetCode, Go, Medium, Find First and Last Position of Element in Sorted Array, Array, Binary Search]
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categories: [LeetCode]
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featuredImage: ""
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featuredImagePreview: ""
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hiddenFromHomePage: false
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hiddenFromSearch: false
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twemoji: false
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lightgallery: true
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ruby: true
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fraction: true
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fontawesome: true
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linkToMarkdown: false
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rssFullText: false
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toc:
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enable: true
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auto: true
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code:
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copy: true
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maxShownLines: 200
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math:
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enable: false
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# ...
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mapbox:
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enable: true
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library:
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css:
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# someCSS = "some.css"
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# located in "assets/"
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# Or
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# someCSS = "https://cdn.example.com/some.css"
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js:
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# someJS = "some.js"
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# located in "assets/"
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# Or
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# someJS = "https://cdn.example.com/some.js"
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seo:
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images: []
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# ...
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---
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# [0034. Find First and Last Position of Element in Sorted Array](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/description/)
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## 題目
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## 題目大意
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## 解題思路
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## Big O
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* 時間複雜 : `O(log(n))`
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* 空間複雜 : `O(1)`
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## 來源
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* https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/description/
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* https://leetcode.cn/problems/find-first-and-last-position-of-element-in-sorted-array/description/
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## 解答
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https://github.com/kimi0230/LeetcodeGolang/blob/master/Leetcode/0034.Find-First-and-Last-Position-of-Element-in-Sorted-Array/main.go
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```go
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package findfirstandlastpositionofelementinsortedarray
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// 時間複雜 O(log(n)), 空間複雜 O(1)
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func searchRange(nums []int, target int) []int {
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result := []int{}
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// first index
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left, right := 0, len(nums)-1
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for left < right {
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mid := int(uint(left+right) >> 1) // [0,1] => 0
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if nums[mid] < target {
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left = mid + 1
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} else if nums[mid] > target {
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right = mid - 1
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} else {
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right = mid
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}
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}
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if left == right && nums[left] == target {
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result = append(result, left)
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} else {
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result = append(result, -1)
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}
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// last index
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left, right = 0, len(nums)-1
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for left < right {
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mid := int(uint(left+right+1) >> 1) // [0,1] => 1
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if nums[mid] < target {
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left = mid + 1
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} else if nums[mid] > target {
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right = mid - 1
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} else {
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left = mid
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}
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}
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if left == right && nums[left] == target {
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result = append(result, left)
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} else {
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result = append(result, -1)
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}
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return result
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}
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```
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## Benchmark
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```sh
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```

‎Leetcode/0034.Find-First-and-Last-Position-of-Element-in-Sorted-Array/main.go

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package findfirstandlastpositionofelementinsortedarray
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// 時間複雜 O(log(n)), 空間複雜 O(1)
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func searchRange(nums []int, target int) []int {
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result := []int{}
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// first index
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left, right := 0, len(nums)-1
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for left < right {
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mid := int(uint(left+right) >> 1) // [0,1] => 0
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if nums[mid] < target {
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left = mid + 1
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} else if nums[mid] > target {
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right = mid - 1
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} else {
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right = mid
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}
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}
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if left == right && nums[left] == target {
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result = append(result, left)
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} else {
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result = append(result, -1)
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}
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// last index
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left, right = 0, len(nums)-1
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for left < right {
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mid := int(uint(left+right+1) >> 1) // [0,1] => 1
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if nums[mid] < target {
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left = mid + 1
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} else if nums[mid] > target {
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right = mid - 1
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} else {
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left = mid
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}
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}
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if left == right && nums[left] == target {
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result = append(result, left)
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} else {
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result = append(result, -1)
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}
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return result
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}

‎Leetcode/0034.Find-First-and-Last-Position-of-Element-in-Sorted-Array/main_test.go

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package findfirstandlastpositionofelementinsortedarray
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import "testing"
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var tests = []struct {
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nums []int
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target int
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want []int
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}{
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{[]int{5, 7, 7, 8, 8, 10}, 8, []int{3, 4}},
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{[]int{5, 7, 7, 8, 8, 10}, 6, []int{-1, -1}},
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{[]int{}, 0, []int{-1, -1}},
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{[]int{1}, 1, []int{0, 0}},
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}
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func TestSearchRange(t *testing.T) {
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for _, tt := range tests {
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got := searchRange(tt.nums, tt.target)
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if got[0] != tt.want[0] || got[1] != tt.want[1] {
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t.Errorf("searchRange(%v, %v) = %v, want %v", tt.nums, tt.target, got, tt.want)
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}
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}
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}
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func BenchmarkSearchRange(b *testing.B) {
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for i := 0; i < b.N; i++ {
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for _, tt := range tests {
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searchRange(tt.nums, tt.target)
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}
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}
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}

‎Leetcode_labuladong/34.在排序数组中查找元素的第一个和最后一个位置.go

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// 時間複雜度:
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// 空間複雜度:
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/*
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* @lc app=leetcode.cn id=34 lang=golang
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*
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* [34] 在排序数组中查找元素的第一个和最后一个位置
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*/
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// @lc code=start
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func searchRange(nums []int, target int) []int {
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result := []int{}
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// first index
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left, right := 0, len(nums)-1
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for left < right {
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mid := int(uint(left+right) >> 1) // [0,1] => 0
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if nums[mid] < target {
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left = mid + 1
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} else if nums[mid] > target {
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right = mid - 1
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} else {
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right = mid
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}
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}
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if left == right && nums[left] == target {
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result = append(result, left)
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} else {
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result = append(result, -1)
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}
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// last index
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left, right = 0, len(nums)-1
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for left < right {
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mid := int(uint(left+right+1) >> 1) // [0,1] => 1
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if nums[mid] < target {
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left = mid + 1
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} else if nums[mid] > target {
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right = mid - 1
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} else {
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left = mid
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}
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}
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if left == right && nums[left] == target {
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result = append(result, left)
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} else {
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result = append(result, -1)
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}
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return result
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}
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// @lc code=end
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‎README.md

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```
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**將搜尋區間全部統一成兩端都閉**, 方便記憶
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`[letf,right]`
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```go
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func Search(nums []int, target int) int {
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return right
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}
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```
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| No. | Title | Solution | Difficulty | Time | Space | Topic |
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|-------------------------------------------------------------------------------------------------------|:----------------------------------------------------------------------------------------------------------------------------:|:---------------------------------------------------------------------------------------------------------------:|------------|---------------------------------------|-------------------------------|---------------|
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| [0704](https://kimi0230.github.io/LeetcodeGolang/Leetcode/0704.Binary-Search/) | [704. Binary Search](https://leetcode.com/problems/binary-search/) | [Go](https://github.com/kimi0230/LeetcodeGolang/tree/master/Leetcode/0704.Binary-Search) | Easy | 最差:O(long n)<br> 最佳O(1)剛好在中間 | 迭代: O(1) <br/> 遞迴O(log n) | Binary Search |
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| [0875](https://kimi0230.github.io/LeetcodeGolang/Leetcode/0875.Koko-Eating-Bananas/) | [875. Koko Eating Bananas](https://leetcode.com/problems/koko-eating-bananas/description/) | [Go](https://github.com/kimi0230/LeetcodeGolang/tree/master/Leetcode/0875.Koko-Eating-Bananas) | Medium | O（n log m） | O(1) | Binary Search |
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| [0153](https://kimi0230.github.io/LeetcodeGolang/Leetcode/0153.Find-Minimum-in-Rotated-Sorted-Array/) | [153. Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/) | [Go](https://github.com/kimi0230/LeetcodeGolang/tree/master/Leetcode/0153.Find-Minimum-in-Rotated-Sorted-Array) | Medium | O(log n） | O(1) | Binary Search |
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| [0033](https://kimi0230.github.io/LeetcodeGolang/Leetcode/0033.Search-in-Rotated-Sorted-Array/) | [33. Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/description//) | [Go](https://github.com/kimi0230/LeetcodeGolang/tree/master/Leetcode/0033.Search-in-Rotated-Sorted-Array) | Medium | O(log n） | O(1) | Binary Search |
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`for left <= right {}`：
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* 此方法在迭代終止時，left 和 right 指針指向同一個位置。
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* 此方法會包括最後一個可能的候選解，在某些情況下可能更容易理解和實現。
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* 在應對邊界情況時可能更為方便，例如當 left 和 right 指向同一位置時，這時可能需要進一步處理。
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`for left < right {}`：
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* 此方法在迭代終止時，left 和 right 指針指向相鄰位置。
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* 此方法會排除最後一個可能的候選解，當要求嚴格小於或大於某個值時可能更合適。
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* 在一些情況下，可能會更高效，因為在每次循環中只需要比較一次 left 和 right，而不需要再處理當兩者相等時的情況。
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| No. | Title | Solution | Difficulty | Time | Space | Topic |
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|--------------------------------------------------------------------------------------------------------------------------|:-----------------------------------------------------------------------------------------------------------------------------------------------------------------:|:----------------------------------------------------------------------------------------------------------------------------------:|------------|---------------------------------------|-------------------------------|---------------|
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| [0704](https://kimi0230.github.io/LeetcodeGolang/Leetcode/0704.Binary-Search/) | [704. Binary Search](https://leetcode.com/problems/binary-search/) | [Go](https://github.com/kimi0230/LeetcodeGolang/tree/master/Leetcode/0704.Binary-Search) | Easy | 最差:O(long n)<br> 最佳O(1)剛好在中間 | 迭代: O(1) <br/> 遞迴O(log n) | Binary Search |
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| [0875](https://kimi0230.github.io/LeetcodeGolang/Leetcode/0875.Koko-Eating-Bananas/) | [875. Koko Eating Bananas](https://leetcode.com/problems/koko-eating-bananas/description/) | [Go](https://github.com/kimi0230/LeetcodeGolang/tree/master/Leetcode/0875.Koko-Eating-Bananas) | Medium | O（n log m） | O(1) | Binary Search |
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| [0153](https://kimi0230.github.io/LeetcodeGolang/Leetcode/0153.Find-Minimum-in-Rotated-Sorted-Array/) | [153. Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/) | [Go](https://github.com/kimi0230/LeetcodeGolang/tree/master/Leetcode/0153.Find-Minimum-in-Rotated-Sorted-Array) | Medium | O(log n） | O(1) | Binary Search |
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| [0033](https://kimi0230.github.io/LeetcodeGolang/Leetcode/0033.Search-in-Rotated-Sorted-Array/) | [33. Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/description//) | [Go](https://github.com/kimi0230/LeetcodeGolang/tree/master/Leetcode/0033.Search-in-Rotated-Sorted-Array) | Medium | O(log n） | O(1) | Binary Search |
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| [0034](https://kimi0230.github.io/LeetcodeGolang/Leetcode/0034.Find-First-and-Last-Position-of-Element-in-Sorted-Array/) | [34. Find First and Last Position of Element in Sorted Array](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/description/) | [Go](https://github.com/kimi0230/LeetcodeGolang/tree/master/Leetcode/0034.Find-First-and-Last-Position-of-Element-in-Sorted-Array) | Medium | O(log n） | O(1) | Binary Search |
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