程式語言 - LeetCode - C - 338. Counting Bits

題目：


解答：

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
int* countBits(int n, int* returnSize)
{
    int c0 = 0;
    int c1 = 0;
    int *r = malloc(sizeof(int) * (n + 1));

    *returnSize = n + 1;
    memset(r, 0, sizeof(int) * (n + 1));

    for (c0 = 0; c0 <= n; c0++) {
        int val = c0;

        for (c1 = 0; c1 < 64; c1++) {
            r[c0] += (val & 1);
            val >>= 1;
        }
    }
    return r;
}