mirror of
https://github.com/krahets/hello-algo.git
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e720aa2d24
* Sync recent changes to the revised Word. * Revised the preface chapter * Revised the introduction chapter * Revised the computation complexity chapter * Revised the chapter data structure * Revised the chapter array and linked list * Revised the chapter stack and queue * Revised the chapter hashing * Revised the chapter tree * Revised the chapter heap * Revised the chapter graph * Revised the chapter searching * Reivised the sorting chapter * Revised the divide and conquer chapter * Revised the chapter backtacking * Revised the DP chapter * Revised the greedy chapter * Revised the appendix chapter * Revised the preface chapter doubly * Revised the figures
34 lines
765 B
Go
34 lines
765 B
Go
// File: two_sum.go
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// Created Time: 2022-11-25
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// Author: reanon (793584285@qq.com)
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package chapter_searching
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/* 方法一：暴力枚举 */
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func twoSumBruteForce(nums []int, target int) []int {
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size := len(nums)
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// 两层循环，时间复杂度为 O(n^2)
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for i := 0; i < size-1; i++ {
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for j := i + 1; i < size; j++ {
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if nums[i]+nums[j] == target {
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return []int{i, j}
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}
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}
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}
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return nil
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}
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/* 方法二：辅助哈希表 */
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func twoSumHashTable(nums []int, target int) []int {
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// 辅助哈希表，空间复杂度为 O(n)
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hashTable := map[int]int{}
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// 单层循环，时间复杂度为 O(n)
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for idx, val := range nums {
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if preIdx, ok := hashTable[target-val]; ok {
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return []int{preIdx, idx}
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}
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hashTable[val] = idx
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}
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return nil
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}
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