hash+set Codeforces Round #291 (Div. 2) C. Watto and Mechanism

 

题目传送门

/*
    hash+set：首先把各个字符串的哈希值保存在set容器里，然后对于查询的每一个字符串的每一位进行枚举
        用set的find函数查找是否存在替换后的字符串，理解后并不难。另外，我想用64位的自然溢出wa了，不清楚
*/
/************************************************
* Author        :Running_Time
* Created Time  :2015-8-5 13:05:49
* File Name     :D.cpp
 ************************************************/

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <cstdlib>
#include <ctime>
using namespace std;

#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
typedef long long ll;
const int MAXN = 6e5 + 10;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
const int KEY = 257;
char s[MAXN];
set<ll> S;
ll ha[MAXN];
int n, m;

void init(void) {
    ha[0] = 1;
    for (int i=1; i<MAXN; ++i)  ha[i] = ha[i-1] * KEY % MOD;
}

ll get_hash(char *s)    {
    int len = strlen (s);
    ll res = 0;
    for (int i=0; i<len; ++i)  {
        res = (res * KEY + s[i]) % MOD;
    }
    return res;
}

bool judge(char *s) {
    int len = strlen (s);
    ll h = get_hash (s);
    for (int i=0; i<len; ++i)   {
        for (ll ch='a'; ch<='c'; ++ch)    {
            if (ch == s[i])   continue;
            if (S.find ((((ch-s[i]) * ha[len-i-1] + h) % MOD + MOD) % MOD) != S.end ())    return true;
        }
    }
    return false;
}

int main(void)    {     //Codeforces Round #291 (Div. 2) C. Watto and Mechanism
    init ();
    while (scanf ("%d%d", &n, &m) == 2) {
        S.clear ();
        for (int i=1; i<=n; ++i)    {
            scanf ("%s", s);
            S.insert (get_hash (s));
        }
        for (int i=1; i<=m; ++i)    {
            scanf ("%s", s);
            if (judge (s))  puts ("YES");
            else    puts ("NO");
        }
    }

    return 0;
}