README.md

977. Squares of a Sorted Array

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

Example 1:

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

Example 2:

Input: [-7,-3,2,3,11]
Output: [4,9,9,49,121]

Note:

1. 1 <= A.length <= 10000
2. -10000 <= A[i] <= 10000
3. A is sorted in non-decreasing order.

Solutions (Rust)

1. Sort

impl Solution {
    pub fn sorted_squares(a: Vec<i32>) -> Vec<i32> {
        let mut squares: Vec<i32> = a.iter().map(|&x| x * x).collect();
        squares.sort_unstable();
        squares
    }
}

2. Two Pointers

impl Solution {
    pub fn sorted_squares(a: Vec<i32>) -> Vec<i32> {
        let mut ret = Vec::new();

        let mut p = a.binary_search(&0).unwrap_or_else(|x| x);
        let mut n = p;
        while n > 0 || p < a.len() {
            if n == 0 || (p < a.len() && a[p] < -a[n - 1]) {
                ret.push(a[p] * a[p]);
                p += 1;
            } else {
                ret.push(a[n - 1] * a[n - 1]);
                n -= 1;
            }
        }

        ret
    }
}