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

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題目：


解答：

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

    *returnSize = n + 1;
    for (i = 0; i <= n; i++) {
        int val = i;

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