[字符串哈希]A. 【例题1】字符串哈希

题目来源 ：YbtOJ

「字符串算法」第2章 Hash 和 Hash 表课堂过关
题面链接

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解题思路

这道题是字符串哈希的模板题， 通过哈希函数来统计有了的字符串

Code

#include <bits/stdc++.h>
#define MOD 100000007
#define N 13313
#define ll long long
using namespace std;

int n, ans;
string s, hd[N];

int hash ()
{
	ll len = s.length (), hhd = 0;
	for (int i = 0; i < len; ++ i)
		hhd = (hhd * 67 % MOD + int (s[i])) % MOD;
	hhd %= N;
	if (hd[hhd] == s) return 1;
	if (hd[hhd] != "")
	{
		ll i = hhd + 1;
		i %= N;
		while (i != hhd)
		{
			if (hd[i] == s) return 1;
			if (hd[i] == "") 
			{
				hd[i] = s;
				return 0;	
			} 
			i = (i + 1) % N;
		}	
	}	
	hd[hhd] = s;
	return 0;
}

int main ()
{
	scanf ("%d", &n);
	for (int i = 1; i <= n; ++ i)
	{
		cin >> s;
		if (!hash ()) ans ++;
	}
	printf ("%d", ans);
	return 0;
}