Learning Recursion based Permutations

 I'm revising recursion again today. I've already learned it this way, but I need to revise it this way again. Yesterday I learned Grady Algorithms. I had to learn recursion again because this topic is a little difficult, but not impossible. It is quite true that backtracking is perfect for recursion-based permutations. I am learning this because I am trying to solve LeetCode question 46. 

Finally, I found the solution:

Pardon me if any misslogic,

var permute = function(nums) {

let ans = []

let i=0

let n=nums.length-1

getPerm(nums, ans, i, n)

return ans

};

let getPerm = (nums, ans, idx, n) => {

    

    if(idx === n) {

        ans.push([...ans])

        return

    }

    for(let i=idx; i<n; i++) {

        

        let tmp = nums[idx]

        nums[idx] = nums[i]

        nums[i] = tmp

        // recursion

        
        getPerm(nums, ans, idx+1, n)

        // backtracing

        tmp = nums[idx]

        nums[idx] = nums[i]

        nums[i] = tmp

    }

}