POJ 3349 Snowflake Snow Snowflakes

#include<iostream>
#include <algorithm>
#include <stdio.h>
#include <cstdio>

using namespace std;

#define size 100010

int arr[size][6];
int n;

struct node{
    int key;
    node *next;
};

node HashTable[size];
node HashPool[size];
int index = 0;

node *getNewNode()
{
    return &HashPool[index++];
}

void insert(int key,node *newNode)
{
    node *tmp = &HashTable[key];
    newNode->next = tmp->next;
    tmp->next = newNode;
}

bool isSame(int a,int b)
{
    sort(arr[a],arr[a]+6);
    sort(arr[b],arr[b]+6);
    for(int i = 0; i < 6;i++)
    {
        if(arr[a][i] != arr[b][i])
            return false;
    }

    return true;
}

int getKey(int a[6])
{
    int sum = 0;
    for(int i = 0; i < 6; i++)
        sum += a[i];

    return sum%99991;
}
bool search(int key,int i)
{
    node *tmp = &HashTable[key];
    tmp = tmp -> next;
    while(tmp != NULL)
    {
        int j = tmp->key;
        tmp = tmp->next;
        if(isSame(i,j))
            return true;
    }

    return false;

}

int main()
{
    scanf("%d",&n);
    for(int i = 0; i < n; i++)
    {
        for(int j = 0; j < 6; j++)
        {
            scanf("%d",&arr[i][j]);
        }
    }

    for(int i = 0; i < n ;i++)
    {
        int key = getKey(arr[i]);
        bool flag = search(key,i);
        if(flag)
        {
            printf("%s\n", "Twin snowflakes found.");
            return 0;
        }
        else
        {
            node *newNode = getNewNode();
            newNode->key = i;
            insert(key,newNode);
        }

    }
    printf("%s\n", "No two snowflakes are alike.");
    return 0;
}