题目：

题解：

int* countBits(int n, int* returnSize) {
    int* bits = malloc(sizeof(int) * (n + 1));
    *returnSize = n + 1;
    bits[0] = 0;
    for (int i = 1; i <= n; i++) {
        bits[i] = bits[i & (i - 1)] + 1;
    }
    return bits;
}