Move the zeros to the end

def move_zeros(nums):
    w = 0                              # nums[:w] holds the non-zero values so far
    for r in range(len(nums)):
        if nums[r] != 0:
            nums[w], nums[r] = nums[r], nums[w]
            w += 1
    return nums

#include <vector>
#include <utility>

std::vector<int> solve(std::vector<int> nums) {
    size_t w = 0;                          // nums[0..w) holds the non-zero values so far
    for (size_t r = 0; r < nums.size(); ++r)
        if (nums[r] != 0) std::swap(nums[w++], nums[r]);
    return nums;
}

class Solution {
    public int[] moveZeros(int[] nums) {
        int w = 0;                             // nums[0..w) holds the non-zero values so far
        for (int r = 0; r < nums.length; r++) {
            if (nums[r] != 0) { int t = nums[w]; nums[w] = nums[r]; nums[r] = t; w++; }
        }
        return nums;
    }
}

function moveZeros(nums) {
  let w = 0;                             // nums[0..w) holds the non-zero values so far
  for (let r = 0; r < nums.length; r++) {
    if (nums[r] !== 0) { [nums[w], nums[r]] = [nums[r], nums[w]]; w++; }
  }
  return nums;
}

fn solve(nums: &[i64]) -> Vec<i64> {
    let mut v = nums.to_vec();
    let mut w = 0;                         // v[..w] holds the non-zero values so far
    for r in 0..v.len() {
        if v[r] != 0 { v.swap(w, r); w += 1; }
    }
    v
}

-- Lists cannot be changed in place, so the stable split is written directly:
-- the non-zero values in order, then the zeros.
solve :: [Int] -> [Int]
solve xs = filter (/= 0) xs ++ filter (== 0) xs