LeetCode 977: Squares of a Sorted Array Solution

Let’s tackle LeetCode 977: Squares of a Sorted Array. Yeah, if you’ve spent any time on LeetCode, you know where we’re headed with this one. It’s all about taking a sorted array of integers, squaring them, and returning them in the same sorted order. Sounds simple, right? Well, there’s always a twist with these problems.

Problem Statement

Given an integer array nums sorted in non-decreasing order, return an array of the squares of each number, also in non-decreasing order.

Example

• Input: nums = [-4,-1,0,3,10]
• Output: [0, 1, 9, 16, 100]

My Solution

Here’s the Java code I cooked up for this problem:

class Solution {
    public int[] sortedSquares(int[] nums) {
        int result[] = new int[nums.length];
        int left = 0;
        int right = nums.length - 1;

        for (int i = nums.length - 1; i >= 0; i--) {
            int square = 0;
            if (Math.abs(nums[left]) > Math.abs(nums[right])) {
                square = nums[left];
                left++;
            } else {
                square = nums[right];
                right--;
            }
            result[i] = square * square;
        }
        return result;
    }
}

Complexity Analysis

• Time Complexity: O(n) — We are only making a single pass through the array.
• Space Complexity: O(n) — We are using a new array to hold the results.

Conclusion

And there you have it! By using a two-pointer technique, we’ve managed to solve this problem in linear time. It’s efficient, neat, and gets the job done without breaking a sweat. Now, all that’s left is to keep grinding those LeetCode problems. If you enjoyed this breakdown or have any questions, feel free to drop a comment!

References

• LeetCode Problem 977 - Squares of a Sorted Array
• Two Pointers Technique Explained

Happy coding! 🖖