哈希 字符串匹配

标签：acm

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <map>
#include <algorithm>
#include <cmath>

using namespace std;
#define maxn 1000000

string s1;
string s2;
int go[maxn];
int Hash;

int pos[maxn];

int Pow(int a, int b)
{
    if(b == 1) return a;
    int x = Pow(a, b>>1);
    long long ans = (long long)x*x;
    if(b & 1) ans = ans*a;
    return (int)ans;
}

void solve()
{
    int len1 = s1.size();
    int len2 = s2.size();
    int b = 13;

    int hashp = 0, hasht = 0;
    for(int i=0; i<len2; i++)
    {
        hashp = (hashp * b + (s2[i] - 'a' + 1)) % 1000007;
        hasht = (hasht * b + (s1[i] - 'a' + 1)) % 1000007;
    }

    for(int i=0; i<len1-len2+1; i++)
    {
        if(hasht == hashp)
            printf("%d ", i+1);

        if(i+len2 < len1)
            hasht =  (hasht*b + (s1[i+len2]-'a'+1) - (s1[i]-'a'+1)*Pow(b, len2)) % 1000007;//注意这里幂函数需要自己写，不然很容易出错
    }
}

int main()
{
    getline(cin, s1);
    getline(cin, s2);

    solve();
    return 0;
}

哈希 字符串匹配

标签：acm

原文地址：http://blog.csdn.net/dojintian/article/details/45169681