Leetcode-Permutations

Given a collection of numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:
[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

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Solution:

Use recursive method. This solution is a iterative recursive solution.

public class Solution {
    public List<List<Integer>> permute(int[] num) {
        int len = num.length;
        List<List<Integer>> resSet = new ArrayList<List<Integer>>();
        List<Integer> curSeq = new ArrayList<Integer>();
        boolean[] used = new boolean[len];
        Arrays.fill(used,false);
        Arrays.sort(num);
        int curIndex = 0;
        curSeq.add(-1);
        while (curIndex!=-1){
            if (curIndex==len){
                List<Integer> temp = new ArrayList<Integer>();
                for (int i=0;i<curSeq.size();i++) temp.add(num[curSeq.get(i)]);
                resSet.add(temp);
                curIndex--;
                continue;
            }
            
            int val = -1;
            if (curSeq.size()>curIndex){
                val = curSeq.get(curIndex);
                if (val!=-1)
                    used[val]=false;
                curSeq.remove(curIndex);
            }

            boolean find = false;
            for (int i=val+1;i<len;i++)
                if (!used[i]){
                    used[i]=true;
                    curSeq.add(i);
                    curIndex++;
                    find = true;
                    break;
                }
            
            if (find)
                continue;
            else 
                curIndex--;
        }

        return resSet;
    }
}