C solution
\nint** findDifference(int* nums1, int nums1Size, int* nums2, int nums2Size, int* returnSize, int** returnColumnSizes){\n    returnColumnSizes[0] = calloc(2, si
```\nint** findDifference(int* nums1, int nums1Size, int* nums2, int nums2Size, int* returnSize, int** returnColumnSizes){\n    returnColumnSizes[0] = calloc(2, sizeof(int));\n    *returnSize = 2;\n    \n    int **ret = malloc(sizeof(int*) * 2);\n    ret[0] = malloc(sizeof(int) * 1000);\n    ret[1] = malloc(sizeof(int) * 1000);\n    int *table = calloc(2001,sizeof(int));\n    \n    for (int i = 0; i < nums2Size; i++)\n        table[nums2[i] + 1000]++;\n    \n    for (int i = 0; i < nums1Size; i++){\n        if (table[nums1[i] + 1000] == 0)\n            ret[0][returnColumnSizes[0][0]++] = nums1[i];\n        table[nums1[i] + 1000] = -1;\n    }\n    \n    for (int i = 0; i < 2001; i++)\n        if (table[i] > 0)\n            ret[1][returnColumnSizes[0][1]++] = i - 1000;\n    \n    free(table);\n    return ret;\n}\n```
['C']