给你一个整数数组 nums 。如果任一值在数组中出现 至少两次 ，返回 true ；如果数组中每个元素互不相同，返回 false 。C语言代码怎么写

bool containsDuplicate(int* nums, int numsSize){
    for(int i=0;i<numsSize;i++){
        for(int j=i+1;j<numsSize;j++){
            if(nums[i]==nums[j]){
                return true;
            }
        }
    }
    return false;
}

或者使用哈希表的方式来优化时间复杂度：

#include <stdbool.h>
#include <stdlib.h>

typedef struct hash_node{
    int val;
    struct hash_node *next;
}hash_node;

typedef struct hash_table{
    int size;
    hash_node **nodes;
}hash_table;

hash_table* create_hash_table(int size){
    hash_table *table = (hash_table*)malloc(sizeof(hash_table));
    table->size = size;
    table->nodes = (hash_node**)calloc(size, sizeof(hash_node*));
    return table;
}

void insert(hash_table *table, int val){
    int key = abs(val) % table->size;

    if(table->nodes[key] == NULL){
        table->nodes[key] = (hash_node*)malloc(sizeof(hash_node));
        table->nodes[key]->val = val;
        table->nodes[key]->next = NULL;
    }
    else{
        hash_node *pre = NULL;
        hash_node *cur = table->nodes[key];

        while(cur != NULL){
            if(cur->val == val){
                return;
            }
            pre = cur;
            cur = cur->next;
        }

        pre->next = (hash_node*)malloc(sizeof(hash_node));
        pre->next->val = val;
        pre->next->next = NULL;
    }
}

bool containsDuplicate(int* nums, int numsSize){
    hash_table *table = create_hash_table(numsSize);

    for(int i=0;i<numsSize;i++){
        insert(table, nums[i]);
    }

    for(int i=0;i<table->size;i++){
        if(table->nodes[i] != NULL){
            if(table->nodes[i]->next != NULL){
                return true;
            }
        }
    }

    return false;
}