题目：

题解：

int cmpfunc(const void *a, const void *b) {
    return (*(int *)a - *(int *)b);
}
//计算组合数*2
int every(int count) {
    if (count == 1) {
        return 0;
    } else {
        return count * (count - 1);
    }
}
//计算每个锚点能产生的回旋镖总数
int part(int *d, int pointsSize) {
    int Sum = 0;
    int count = 1;
    for (int i = 0; i < pointsSize - 1; i++) {
        if (d[i] == d[i + 1]) {
            count++;
        } else {
            Sum += every(count);
            count = 1;
        }
    }
    Sum+=every(count);
    return Sum;
}
//计算总共能产生的回旋镖的数量
int numberOfBoomerangs(int** points, int pointsSize, int* pointsColSize){
    if(pointsSize <= 2){
        return 0;
    }

    int sum = 0;
    
    for(int i = 0; i < pointsSize; i++) {
       
            
                int *d = (int *)malloc((pointsSize) * sizeof(int));
                int *co = d;

                for(int k = 0; k < pointsSize; k++) {
                    
                        *co = pow(points[i][0] - points[k][0], 2) + pow(points[i][1] - points[k][1], 2);
                        co++;
                    
                }

                qsort(d, pointsSize, sizeof(int), cmpfunc);
                sum += part(d, pointsSize);

                free(d);
            
        
        
    }
     return sum;
}