LeetCode 剑指 Offer 17. 打印从1到最大的n位数

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
int* printNumbers(int n, int* returnSize){
    int top, i, j, *nums;

    top = 1; 
    for (i=0; i<n; ++i) {
        top = top * 10;
    }
    *returnSize = top - 1;
    nums = malloc(sizeof(int) * (top - 1));
    memset(nums, 0, sizeof(int) * (top - 1));

    j = 0;
    for (i=1; i<top; ++i) {
        nums[j++] = i;
    }

    return nums;
}