Next Greater Element III

Problem statement

Given a positive integer n, find the smallest integer which has exactly the same digits existing in the integer n and is greater in value than n. If no such positive integer exists, return -1.

Note that the returned integer should fit in 32-bit integer, if there is a valid answer but it does not fit in 32-bit integer, return -1.

Example 1:

Input: n = 12Output: 21

Example 2:

Input: n = 21Output: -1

Constraints:

• 1 <= n <= 231 - 1

My solution

/**
 * @param {number} n
 * @return {number}
 */
var nextGreaterElement = function(n) {
    const arr = n.toString().split("");
    let pivot = -1;
    
    for (let i = arr.length - 1; i > 0; i--) {
        if (arr[i - 1] < arr[i]) {
            pivot = i - 1
            break;
        }
    }
    
    if (pivot === -1) {
        return -1
    }
    
    // console.log("pivot", pivot, arr.length - 1)
    
    for (let i = arr.length - 1; i > pivot; i--) {
        // console.log("i", i, pivot)
        if (arr[i] > arr[pivot]) {
            [arr[pivot], arr[i]] = [arr[i], arr[pivot]]
            break;
        }
    }
    const left = arr.slice(0, pivot + 1)
    // console.log("newNumber", arr)
    const right = arr.slice(pivot + 1)
    right.reverse()
    const newNumber = Number(left.join("") + right.join(""))
    
    return newNumber > Math.pow(2, 31) -1 ? -1 : newNumber;
};