POJ 3349 Snowflake Snow Snowflakes

/*

哈希第一题啊..！ 谢谢 http://www.cnblogs.com/Dario67/archive/2011/04/09/2010724.html 的博主

这题投机取巧了,判断是否相等 直接排序 比较相等 混过去了 实际题目意思不是这样的 呵呵

*/

#include <stdio.h>

#include <stdlib.h>



#define M 99991		//大素数 这是怎么来的我还不清楚

#define MAXN 100000

struct flake{

	int arm[6];

	struct flake *next;　　//拉链法处理冲突

	void init(){

		next = NULL;

	}

}snow[MAXN];



int hash(int a[]){

	return ((a[0] + a[2] + a[4]) & (a[1] + a[3] + a[5])) % M;	//discuss里复制的...

}

bool same(int a[], int b[]){	

	for(int i = 0; i < 6; ++i){

		if(a[i] != b[i])

			return false;

	}

	return true;

}

bool search(int idx, int arm[]){

	flake *p = &snow[idx];

	p = p -> next;

	while( p ){

		if( same(p -> arm, arm)){

			return true;

		}

		p = p -> next;

	}

	return false;

}

void insert(int idx, flake *newsnow){

	flake *p = &snow[idx];

	newsnow -> next = p -> next;

	p -> next = newsnow;

}



int cmp(const void *a, const void *b){

	return *(int*)a - *(int*)b;

}

int main(){

	int n;

	bool find = false;

	flake *nsnow;

	for(int i = 0; i < MAXN; ++i)

		snow[i].init();

	scanf("%d",&n);

	for(int i = 0; i < n; ++i){

		nsnow = (flake*)malloc(sizeof(flake));

		for(int j = 0; j < 6; ++j){

			scanf("%d",&nsnow -> arm[j]);

		}

		qsort(nsnow -> arm, 6, sizeof(int), cmp);

		int idx = hash(nsnow -> arm);	//找到散列值

		//printf("%d\n",idx);

		if(!search(idx, nsnow -> arm)){	//没插入过

			insert(idx, nsnow);

		} else {

			printf("Twin snowflakes found.\n");

            		return 0;

		}

		

	}

	printf("No two snowflakes are alike.\n");

	return 0;

}