程式語言 - LeetCode - C - 2215. Find the Difference of Two Arrays

題目：


解答：

/**
 * Return an array of arrays of size *returnSize.
 * The sizes of the arrays are returned as *returnColumnSizes array.
 * Note: Both returned array and *columnSizes array must be malloced, assume caller calls free().
 */
int** findDifference(int* nums1, int nums1Size, int* nums2, int nums2Size, int* returnSize, int** returnColumnSizes)
{
    #define OFFSET   1000
    #define MAX_SIZE 2001

    int i = 0;
    int idx = 0;
    int s1[MAX_SIZE] = { 0 };
    int s2[MAX_SIZE] = { 0 };
    int **r = calloc(sizeof(int *), 2);

    for (i = 0; i < 2; i++) {
        r[i] = calloc(sizeof(int), MAX_SIZE);
    }

    *returnSize = 2;
    *returnColumnSizes = calloc(sizeof(int), 2);

    for (i = 0; i < nums1Size; i++) {
        s1[nums1[i] + OFFSET] += 1;
    }

    for (i = 0; i < nums2Size; i++) {
        s2[nums2[i] + OFFSET] += 1;
    }

    idx = 0;
    for (i = 0; i < nums1Size; i++) {
        if (s2[nums1[i] + OFFSET] == 0) {
            r[0][idx++] = nums1[i];
            s2[nums1[i] + OFFSET] += 1;
        }
    }
    (*returnColumnSizes)[0] = idx;

    idx = 0;
    for (i = 0; i < nums2Size; i++) {
        if (s1[nums2[i] + OFFSET] == 0) {
            r[1][idx++] = nums2[i];
            s1[nums2[i] + OFFSET] += 1;
        }
    }
    (*returnColumnSizes)[1] = idx;
 
    return r;
}