DFS/回溯算法

回溯算法模板：

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result = [] def backtrack(路径, 选择列表):  if 满⾜结束条件:  result.add(路径)  return  for 选择 in 选择列表:  做选择  backtrack(路径, 选择列表)  撤销选择

　　

力扣46题

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func permute(nums []int) [][]int {     ans := make([][]int, 0)     track := make([]int, 0)     visited := map[int]bool{}     sort.Ints(nums)       var backtrack func()     backtrack = func() {         if len(track) == len(nums) {             ans = append(ans, append([]int{}, track...))             return         }         for i := 0; i < len(nums); i++ {             if visited[i] {                 continue             }             visited[i] = true             track = append(track, nums[i])             backtrack()             visited[i] = false             track = track[:len(track)-1]         }     }     backtrack()     return ans }