题目：

题解：

typedef struct {unsigned long long val;UT_hash_handle hh;
} Hash;typedef struct {Hash *hash;int n_rows;int n_cols;
} Solution, SL;Solution* solutionCreate(int n_rows, int n_cols) {SL *obj = malloc(sizeof(SL));obj->hash = NULL;obj->n_rows = n_rows;obj->n_cols = n_cols;return obj;
}int* solutionFlip(Solution* obj, int* retSize) {*retSize = 2;int *res = malloc(2 * sizeof(int));while (true) {int x = rand() % obj->n_rows;int y = rand() % obj->n_cols;unsigned long long t = x;t <<= 32;t |= y;// printf("%ld\n", t);Hash *p;HASH_FIND(hh, obj->hash, &t, sizeof(unsigned long long), p);if (!p) {res[0] = x;res[1] = y;p = malloc(sizeof(Hash));p->val = t;HASH_ADD(hh, obj->hash, val, sizeof(unsigned long long), p);break;}}return res;
}void solutionReset(Solution* obj) {Hash *cur, *tmp;HASH_ITER(hh, obj->hash, cur, tmp) {HASH_DEL(obj->hash, cur);}
}void solutionFree(Solution* obj) {Hash *cur, *tmp;HASH_ITER(hh, obj->hash, cur, tmp) {HASH_DEL(obj->hash, cur);free(cur);}free(obj);
}/*** Your Solution struct will be instantiated and called as such:* Solution* obj = solutionCreate(n_rows, n_cols);* int* param_1 = solutionFlip(obj, retSize);* solutionReset(obj);* solutionFree(obj);
*/