运行时错误,因为“unsigned int”

试图解决 217. Contains Duplicate 在C中使用HashSet。

在我试图使计算的指数始终为(+)之后,我得到了一个错误。

#define BUCKET_SIZE 1000

typedef struct ListNodes {
  int val;
  struct ListNodes* next;
} ListNode;

typedef struct {
  ListNode* buckets[BUCKET_SIZE];
} MyHashSet;

// create hash table
MyHashSet* myHashSetCreate() {
    MyHashSet* obj = (MyHashSet*) malloc(sizeof(MyHashSet));
    for(int i = 0 ; i < BUCKET_SIZE ; i++ ) {
        obj -> buckets[i] = NULL;
    }
    return obj;
}

bool myHashSet(MyHashSet* obj, int key) {
    unsigned int index =  key % BUCKET_SIZE; // problem here
    ListNode* current = obj->buckets[index];
    while(current != NULL) {
        if(current -> val == key) return true;
        current = current -> next;
    } 
    
    ListNode* newNode = (ListNode*)malloc(sizeof(ListNode));
    newNode->val = key;
    newNode->next = obj->buckets[index];
    obj->buckets[index] = newNode;
    return false;
}

// task function

bool containsDuplicate(int* nums, int numsSize) {
     MyHashSet* obj = myHashSetCreate();
     for(int i = 0 ; i < numsSize ; i++) {
        if(myHashSet(obj, nums[i])) {
            return true;
        }
     }
    return false;
}

unsigned int index = key % BUCKET_SIZE;

后果

第23行:字符15:运行时错误:加载地址0x6258000078f0,空间不足,无法容纳类型为“struct ListNode*”[solution.c]的对象 0x6258000078f0:注意:指针指向此处

ListNode* current = obj->buckets[index];

我通过以下方式修复了错误:

int index = key % BUCKET_SIZE;

或

int index =  key % BUCKET_SIZE;
    if( index < 0) {
        index *= -1;
    }

知道为什么代码的行为很奇怪吗?