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题目：

题解：

/**
 * 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().
 */
struct vat
{
    int start;
    int end;
};

int compare(struct vat* a,struct vat  *b)
{
    return a->start - b->start;
}


int** merge(int** intervals, int intervalsSize, int* intervalsColSize, int* returnSize, int** returnColumnSizes)
{
    struct vat newVat[intervalsSize];
    for(int i =0; i < intervalsSize; i++)
    {
        newVat[i].start = intervals[i][0];
        newVat[i].end   = intervals[i][1];
    }
    qsort(newVat,intervalsSize,sizeof(struct vat),compare);
    


    int **returnInteval = (int **)malloc(sizeof(int *) * intervalsSize);
    *returnColumnSizes  = (int *)malloc(sizeof(int ) * intervalsSize);
    *returnSize = 0;
    for(int i =0; i < intervalsSize; i++)
    {
        if(*returnSize)
        {
            int preEnd = returnInteval[*returnSize-1][1];
            if(newVat[i].start <= preEnd)
            {
                //合并
                int  maxEnd = fmax(preEnd,newVat[i].end);
                returnInteval[*returnSize-1][1] = maxEnd;
            }
            else
            {
                //没有重合的
                int newRow = *returnSize;
                returnInteval[newRow]   = (int *)malloc(sizeof(int ) * 2);
                returnInteval[newRow][0] =  newVat[i].start;
                returnInteval[newRow][1] =  newVat[i].end;
                (*returnColumnSizes)[newRow] = 2;
                *returnSize = *returnSize + 1;
            }
        }
        else
        {
            int newRow = *returnSize;
            returnInteval[newRow]   = (int *)malloc(sizeof(int ) * 2);
            returnInteval[newRow][0] =  newVat[i].start;
            returnInteval[newRow][1] =  newVat[i].end;
            (*returnColumnSizes)[newRow] = 2;
            *returnSize = *returnSize + 1;
            
        }
    }
    return returnInteval;
}