You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
hello-algo/zh-hant/codes/go/chapter_backtracking/permutations_ii.go

42 lines
1.2 KiB

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