leetcode-46-Permutations

Given a collection of distinct integers, return all possible permutations.

Example:

Input: [1,2,3]
Output:
[
  [1,2,3],
  [1,3,2],
  [2,1,3],
  [2,3,1],
  [3,1,2],
  [3,2,1]
]

试探回溯法

class Solution {
    public List<List<Integer>> permute(int[] nums) {
        List<List<Integer>> pms = new ArrayList<>();
        rP(nums, new boolean[nums.length], new ArrayList<Integer>(), pms);
        return pms;
    }
    
    void rP(int[] nums, boolean[] set, List<Integer> pm, List<List<Integer>> pms)
    {
        if(pm.size() == nums.length)
        {
            pms.add(pm);
            return;
        }
        
        for(int i=0; i<nums.length; i++)
        {
            if(set[i]) continue;
            set[i] = true;
            List<Integer> currPm = new ArrayList<>(pm);
            currPm.add(nums[i]);
            rP(nums, set, currPm, pms);
            set[i] = false;
        }
    }
}