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Merge pull request #572 from hitorig/master

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Update 0046.全排列.md，更新了golang代码（原来的缺少permute函数）使用了切片思路 以及 第47题golang代码也有问题，同修改
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程序员Carl
2021-08-08 15:30:58 +08:00
committed by GitHub
parent 46101335c0 31ddd23e1d
commit f3041a5a2b
2 changed files with 43 additions and 44 deletions
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33
problems/0046.全排列.md
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@ -227,23 +227,26 @@ class Solution:
Go： Go：
```Go ```Go
var result [][]int var res [][]int
func backtrack(nums,pathNums []int,used []bool){ func permute(nums []int) [][]int {
if len(nums)==len(pathNums){ res = [][]int{}
tmp:=make([]int,len(nums)) backTrack(nums,len(nums),[]int{})
copy(tmp,pathNums) return res
result=append(result,tmp)
//result=append(result,pathNums)
return
} }
for i:=0;i<len(nums);i++{ func backTrack(nums []int,numsLen int,path []int) {
if !used[i]{ if len(nums)==0{
used[i]=true p:=make([]int,len(path))
pathNums=append(pathNums,nums[i]) copy(p,path)
backtrack(nums,pathNums,used) res = append(res,p)
pathNums=pathNums[:len(pathNums)-1]
used[i]=false
} }
for i:=0;i<numsLen;i++{
cur:=nums[i]
path = append(path,cur)
nums = append(nums[:i],nums[i+1:]...)//直接使用切片
backTrack(nums,len(nums),path)
nums = append(nums[:i],append([]int{cur},nums[i:]...)...)//回溯的时候切片也要复原，元素位置不能变
path = path[:len(path)-1]
} }
} }

38
problems/0047.全排列II.md
View File

@ -229,34 +229,30 @@ Go：
var res [][]int var res [][]int
func permute(nums []int) [][]int { func permute(nums []int) [][]int {
res = [][]int{} res = [][]int{}
sort.Ints(nums) backTrack(nums,len(nums),[]int{})
dfs(nums, make([]int, 0), make([]bool, len(nums)))
return res return res
} }
func backTrack(nums []int,numsLen int,path []int) {
func dfs(nums, path []int, used []bool) { if len(nums)==0{
if len(path) == len(nums) { p:=make([]int,len(path))
res = append(res, append([]int{}, path...)) copy(p,path)
return res = append(res,p)
} }
used := [21]int{}//跟前一题唯一的区别，同一层不使用重复的数。关于used的思想carl在递增子序列那一题中提到过
m := make(map[int]bool) for i:=0;i<numsLen;i++{
for i := 0; i < len(nums); i++ { if used[nums[i]+10]==1{
// used 从剩余 nums 中选
if used[i] {
continue continue
} }
// m 集合间去重 cur:=nums[i]
if _, ok := m[nums[i]]; ok { path = append(path,cur)
continue used[nums[i]+10]=1
} nums = append(nums[:i],nums[i+1:]...)
m[nums[i]] = true backTrack(nums,len(nums),path)
path = append(path, nums[i]) nums = append(nums[:i],append([]int{cur},nums[i:]...)...)
used[i] = true
dfs(nums, path, used)
used[i] = false
path = path[:len(path)-1] path = path[:len(path)-1]
} }
} }
``` ```