TheAlgorithms-C/leetcode/src/905.c

/**
 * 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: The returned array must be malloced, assume caller calls free().
 */
int* sortArrayByParity(int* A, int ASize, int* returnSize) {
    int *retArr = malloc(ASize * sizeof(int));
    int oddIndex = ASize - 1;
    int evenIndex = 0;
    *returnSize = ASize;
    for (int i = 0; i < ASize; i++) {
        if (A[i] % 2 == 0) {
            retArr[evenIndex] = A[i];
            evenIndex++;
        } else {
            retArr[oddIndex] = A[i];
            oddIndex--;
        }
    }

    return retArr;
}