leetcode/work/Easy/Array/977.squares-of-a-sorted-array.js

/*
 * 977. Squares of a Sorted Array
 * Difficulty: Easy
 * https://leetcode.com/problems/squares-of-a-sorted-array/
 * 
 * ──────────────────────────────────────────────────
 * 
 * Given an integer array nums sorted in non-decreasing order, return an
 * array of the squares of each number sorted in non-decreasing order.
 * 
 *  
 * 
 * Example 1:
 * 
 * Input: nums = [-4,-1,0,3,10]
 * Output: [0,1,9,16,100]
 * Explanation: After squaring, the array becomes [16,1,0,9,100].
 * After sorting, it becomes [0,1,9,16,100].
 * 
 * Example 2:
 * 
 * Input: nums = [-7,-3,2,3,11]
 * Output: [4,9,9,49,121]
 * 
 *  
 * 
 * Constraints:
 * 
 * 	• 1 <= nums.length <= 10^4
 * 
 * 	• -10^4 <= nums[i] <= 10^4
 * 
 * 	• nums is sorted in non-decreasing order.
 * 
 *  
 * 
 * Follow up: Squaring each element and sorting the new array is very
 * trivial, could you find an O(n) solution using a different approach?
*/

/**
 * @param {number[]} nums
 * @return {number[]}
 */
var sortedSquares = function(nums) {
  let n = nums.length;
  let ans = new Array(nums.length);
  let left = 0, right = nums.length - 1;

  for (let i = n -1; i >= 0; i--){
    let square;
    if(Math.abs(nums[left]) < Math.abs(nums[right])){
      square = nums[right];
      right--;
    }else{
      square = nums[left];
      left++;
    }
    ans[i] = square*square;
  }
  return ans;
};