leetcode-170. 两数之和 III - 数据结构设计-C语言

/*
 * 算法思想： 与两数之和相同，查找某时，重新建立hash table，查找完后销毁。
 */

typedef struct has_node{
    int key;
    struct has_node *next;
}HNode;

#define LEN 0xffff

void hash_insert(HNode **hb, int key) {
    int index = abs(key % LEN);
    
    HNode *node = (HNode *)malloc(sizeof(HNode));
    node->key = key;
    node->next = hb[index];
    hb[index] = node;
}

HNode *hash_find(HNode **hb, int key) {
     int index = abs(key % LEN);
    
    HNode *node = hb[index];
    while(node){
        if(node->key == key) {
            break;
        }
        node = node->next;
    }
    return node;
}

void hash_init(HNode **hb){
    int i;
    for(i=0; inext;
            
            free(last);
        }
    }
    
}

typedef struct {
    HNode **hb;
    int *stack;
    int stack_index;
} TwoSum;

/** Initialize your data structure here. */

TwoSum* twoSumCreate() {
    TwoSum* obj= (TwoSum*)malloc(sizeof(TwoSum));
    obj->hb = (HNode **)malloc(sizeof(HNode *) * LEN);
    obj->stack = (int *)malloc(sizeof(int) * LEN);
    obj->stack_index = 0;
    
    return obj;
}

/** Add the number to an internal data structure.. */
void twoSumAdd(TwoSum* obj, int number) {
  obj->stack[obj->stack_index++] = number;
}

/** Find if there exists any pair of numbers which sum is equal to the value. */
bool twoSumFind(TwoSum* obj, int value) {
    int i;
    bool ret = false;
    
    hash_init(obj->hb);  

    for(i=0; istack_index; i++){
        if(hash_find(obj->hb, value-obj->stack[i])) {
            ret = true;
            break;
        }
        hash_insert(obj->hb, obj->stack[i]);
    }

    hash_exit(obj->hb);
    
    return ret;
}

void twoSumFree(TwoSum* obj) {
    free(obj->stack);
    free(obj->hb);
    free(obj);
}

/**
 * Your TwoSum struct will be instantiated and called as such:
 * TwoSum* obj = twoSumCreate();
 * twoSumAdd(obj, number);
 
 * bool param_2 = twoSumFind(obj, value);
 
 * twoSumFree(obj);
*/