README.md

905. Sort Array By Parity

Given an array A of non-negative integers, return an array consisting of all the even elements of A, followed by all the odd elements of A.

You may return any answer array that satisfies this condition.

Example 1:

Input: [3,1,2,4]
Output: [2,4,3,1]
The outputs [4,2,3,1], [2,4,1,3], and [4,2,1,3] would also be accepted.

Note:

1. 1 <= A.length <= 5000
2. 0 <= A[i] <= 5000

Solutions (Rust)

1. Two Pointers

impl Solution {
    pub fn sort_array_by_parity(a: Vec<i32>) -> Vec<i32> {
        let mut a = a;
        let mut i = 0;
        let mut j = a.len() - 1;
        while i < j {
            while i < j && a[i] % 2 == 0 {
                i += 1;
            }
            while i < j && a[j] % 2 == 1 {
                j -= 1;
            }
            a.swap(i, j);
        }
        a
    }
}

2. One Pass

impl Solution {
    pub fn sort_array_by_parity(a: Vec<i32>) -> Vec<i32> {
        let mut even = Vec::new();
        let mut odd = Vec::new();
        for n in a {
            match n % 2 == 0 {
                true => even.push(n),
                false => odd.push(n),
            };
        }
        even.append(&mut odd);
        even
    }
}

3. Sort

impl Solution {
    pub fn sort_array_by_parity(a: Vec<i32>) -> Vec<i32> {
        let mut a = a;
        a.sort_unstable_by_key(|k| k % 2 == 1);
        a
    }
}