e2570 v1.c

/**
 * 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** mergeArrays(int** nums1, int nums1Size, int* nums1ColSize, int** nums2, int nums2Size, int* nums2ColSize, int* returnSize, int** returnColumnSizes){
    // To act in effect as a hashmap of size 1001 so we can just place 
    // the vals here temporarily
    int** output = (int**) malloc(sizeof(int*) * (1000 + 1));

    // Initializing and setting space
    for (int i = 0; i < 1000 + 1; i++) {
        output[i] = (int*) malloc(sizeof(int) * 2);
        output[i][0] = 0;
    }


    // Going through each of the input vals
    int numValsInOutput = 0;

    for (int i = 0; i < nums1Size; i++) {
        if (output[nums1[i][0]][0] == 0) {
            output[nums1[i][0]][0] = nums1[i][0];
            output[nums1[i][0]][1] = nums1[i][1];
            numValsInOutput++;
        } else {
            output[nums1[i][0]][1] += nums1[i][1];
        }
    }

    for (int i = 0; i < nums2Size; i++) {
        if (output[nums2[i][0]][0] == 0) {
            output[nums2[i][0]][0] = nums2[i][0];
            output[nums2[i][0]][1] = nums2[i][1];
            numValsInOutput++;
        } else {
            output[nums2[i][0]][1] += nums2[i][1];
        }
    }

    // Mallocing and filling the actual output space
    int** realOutput = (int**) malloc(sizeof(int*) * numValsInOutput);
    *returnSize = numValsInOutput;
    *returnColumnSizes = (int*) malloc(sizeof(int) * numValsInOutput);

    int pos = 0;
    int outputPos = 0;
    while (pos < numValsInOutput) {
        if (output[outputPos][0] != 0) {
            realOutput[pos] = (int*) malloc(sizeof(int) * 2);
            realOutput[pos][0] = output[outputPos][0];
            realOutput[pos][1] = output[outputPos][1];
            (*returnColumnSizes)[pos] = 2;
            pos++;
        }
        outputPos++;
    }


    // Freeing our previous values
    for (int i = 0; i < nums1Size + nums2Size; i++) {
        free(output[i]);    
    }
    free(output);

    return realOutput;
}