LA 3942 字典树

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<stdlib.h>
#include<math.h>
#include<queue>
#include<vector>
#include<map>

const int maxnode=501000;
const int maxn=300100;
const int mod=20071027;

using namespace std;

int n,cas,d[maxn];
char s[maxn];
struct Trie
{
    int ch[maxnode][26];
    bool val[maxnode];
    int sz;
    Trie(){sz=1;memset(ch[0],0,sizeof(ch[0]));}
    void reset(){sz=1;memset(ch[0],0,sizeof(ch[0]));}
    int idx(char x){return x-'a';}
    void insert(char *nw,int v)
    {
        int u=0,l=strlen(nw);
        for(int i=0;i<l;i++)
        {
            int x=idx(nw[i]);
            if (!ch[u][x]){
                memset(ch[sz],0,sizeof(ch[sz]));//边更新，边初始化
                val[sz]=0;
                ch[u][x]=sz++;
            }
            u=ch[u][x];
        }
        val[u]=v;
    }
    int search(int st)//查找s[i...len-1]的所有前缀
    {
        int u=0,l=strlen(s);
        int ans=0;
        for(int i=st;i<l;i++)
        {
            int x=idx(s[i]);
            if (!ch[u][x]) return ans;
            u=ch[u][x];
            if(val[u])ans=(ans+d[i+1])%mod;//i+1是计算化简后的,记住标记
        }
        return ans;
    }
}tree;//tree的定义要放到main的外面

int main()
{
    cas=0;
    while(scanf("%s",s)==1)
    {
        scanf("%d",&n);
        cas++;
        tree.reset();
        char word[maxn];
        for(int i=0;i<n;i++)
        {
            cin>>word;tree.insert(word,1);
        }
        int len=strlen(s);
        memset(d,0,sizeof(d));
        d[len]=1;
        for(int i=len-1;i>=0;i--)
        d[i]=tree.search(i);
        printf("Case %d: %d
",cas,d[0]);
//        cout<<"Case "<<cas<<": "<<d[0]<<endl;
    }
    return 0;
}