给定一个不含重复数字的数组 nums ，返回其 所有可能的全排列 。你可以 按任意顺序 返回

class Solution {

public List<List<Integer>> permute(int[] nums) {
    List<List<Integer>>  result = new ArrayList<>();
    if(nums.length == 0){
        return result;
    }

    ValueRecord[] valueRecords = new ValueRecord[nums.length];
    for(int i = 0; i<nums.length;i++){
        ValueRecord valueRecord = new ValueRecord();
        valueRecord.value = nums[i];
        valueRecords[i] = valueRecord;
    }
    List<Integer> path = new ArrayList<>();
    dfs(nums, path, valueRecords, result);
    return result;
}

/**
 *
 **/
private void dfs(int[] nums, List<Integer> path, ValueRecord[] valueRecords, List<List<Integer>>  result ){
    if(path.size() == nums.length){
        result.add(new ArrayList(path));
        return;
    }

    for(int currIndex = 0; currIndex<nums.length;currIndex++){
        ValueRecord valueRecord = valueRecords[currIndex];
        if(!valueRecord.isValid){
            continue;
        }
        valueRecord.isValid = false;
        path.add(valueRecord.value);
        dfs(nums, path, valueRecords, result);
        path.remove(path.size()-1);
        valueRecord.isValid = true;
    }
}

public static class ValueRecord{
    int value;
    boolean isValid = true;
}

}