poj-1200-Crazy Search-karp-rabin算法

来源：互联网发布：铣腰形状孔编程编辑：程序博客网时间：2024/05/20 16:34

字符串hash中的karp-rabin算法的应用。

把字符串转换为进制数。

#include<stdio.h>#include<iostream>#include<string.h>#include<algorithm>#include<queue>#include<stack>#include<map>#include<string>#include<stdlib.h>#define INT_MAX 0x7fffffff#define INF 999999#define max3(a,b,c) (max(a,b)>c?max(a,b):c)#define min3(a,b,c) (min(a,b)<c?min(a,b):c)#define mem(a,b) memset(a,b,sizeof(a))using namespace std;struct node{    int u;    int v;    int w;    bool friend operator < (node a, node b){        return a.w < b.w;    }}edge[1001];int gcd(int n,int m){if(n<m) swap(n,m);return n%m==0?m:gcd(m,n%m);}int lcm(int n,int m){if(n<m) swap(n,m);return n/gcd(n,m)*m;}int hash[16000005];char st[16000005];int main(){    int n,nc;    while(~scanf("%d %d %s",&n,&nc,st))    {        int num;        num=0;        mem(hash,0);        int len=strlen(st);        int ns;        ns=nc;        int i;        int t=0;        int name[10000];        for (i =0; i < len; i++)            if (name[st[i]] ==0)                name[st[i]] = t++;        for(i=0;i<n-1;i++)        {            num=num*nc+name[st[i]];            ns=ns*nc;        }        int ans=0;        for(i=n-1;i<len;i++)        {            num=(num*nc+name[st[i]])%ns;            if(!hash[num])ans++;            hash[num]=1;        }        printf("%d\n",ans);    }    return 0;}