给定一个 没有重复 数字的序列，返回其所有可能的全排列。

示例:

输入: [1,2,3] 输出: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1] ]

/**
 * @param {number[]} nums
 * @return {number[][]}
 */
var permute = function(nums) {

    var backtrack = (results, tempList, nums) => {
        if(tempList.length == nums.length){
            return results.push([...tempList]);
        }
        for(let i = 0; i < nums.length; i++){
            if(tempList.includes(nums[i])){
                continue;
            }
            tempList.push(nums[i]);
            backtrack(results, tempList, nums);
            tempList.pop();
        }
    }

    let results = [];
    backtrack(results, [], nums);
    return results;
};