Day-21 Sort Array By Parity

class Solution {
    public int[] sortArrayByParity(int[] A) {
        Integer[] B = new Integer[A.length];
        for (int t = 0; t < A.length; ++t)
            B[t] = A[t];

        Arrays.sort(B, (a, b) -> Integer.compare(a%2, b%2));

        for (int t = 0; t < A.length; ++t)
            A[t] = B[t];
        return A;

        /* Alternative:
        return Arrays.stream(A)
                     .boxed()
                     .sorted((a, b) -> Integer.compare(a%2, b%2))
                     .mapToInt(i -> i)
                     .toArray();
        */
    }
}

class Solution {
    public int[] sortArrayByParity(int[] A) {
        int[] ans = new int[A.length];
        int t = 0;

        for (int i = 0; i < A.length; ++i)
            if (A[i] % 2 == 0)
                ans[t++] = A[i];

        for (int i = 0; i < A.length; ++i)
            if (A[i] % 2 == 1)
                ans[t++] = A[i];

        return ans;
    }
}

class Solution {
    public int[] sortArrayByParity(int[] A) {
        int i = 0, j = A.length - 1;
        while (i < j) {
            if (A[i] % 2 > A[j] % 2) {
                int tmp = A[i];
                A[i] = A[j];
                A[j] = tmp;
            }

            if (A[i] % 2 == 0) i++;
            if (A[j] % 2 == 1) j--;
        }

        return A;
    }
}