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39 lines
1 KiB
Go
39 lines
1 KiB
Go
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// File: permutations_i.go
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// Created Time: 2023-05-14
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// Author: Reanon (793584285@qq.com)
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package chapter_backtracking
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/* 回溯演算法：全排列 I */
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func backtrackI(state *[]int, choices *[]int, selected *[]bool, res *[][]int) {
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// 當狀態長度等於元素數量時，記錄解
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if len(*state) == len(*choices) {
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newState := append([]int{}, *state...)
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*res = append(*res, newState)
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}
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// 走訪所有選擇
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for i := 0; i < len(*choices); i++ {
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choice := (*choices)[i]
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// 剪枝：不允許重複選擇元素
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if !(*selected)[i] {
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// 嘗試：做出選擇，更新狀態
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(*selected)[i] = true
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*state = append(*state, choice)
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// 進行下一輪選擇
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backtrackI(state, choices, selected, res)
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// 回退：撤銷選擇，恢復到之前的狀態
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(*selected)[i] = false
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*state = (*state)[:len(*state)-1]
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}
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}
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}
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/* 全排列 I */
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func permutationsI(nums []int) [][]int {
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res := make([][]int, 0)
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state := make([]int, 0)
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selected := make([]bool, len(nums))
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backtrackI(&state, &nums, &selected, &res)
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return res
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}
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