P3618 误会

链接：Miku

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hash?不不不，kmp走起

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唯一的问题是最后要有一个dp来解决

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#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring> 
using namespace std;
int n;
const int maxn=100001;
char a[maxn],b[maxn];
int la,lb;
int ans,j;
int ne[maxn];
int mod=1000000007;
int pl[maxn];
long long dp[maxn];
int main(){
    scanf("%d",&n);
    for(register int i=1;i<=n;++i){
        scanf("%s%s",a+1,b+1);
        ans=0;
        la=strlen(a+1);
        lb=strlen(b+1);
        memset(dp,0,sizeof(dp));
        memset(pl,0,sizeof(pl));
        memset(ne,0,sizeof(ne));
         j=0;
        ne[0]=ne[1]=0;
        for(register int k=2;k<=lb;++k){
            while(j&&b[k]!=b[j+1]) j=ne[j];
            if(b[k]==b[j+1]) j++;
            ne[k]=j;
        }
        j=0;
        for(register int k=1;k<=la;++k){
            while(j&&a[k]!=b[j+1]) j=ne[j];
            if(a[k]==b[j+1]) j++;
            if(j==lb){
                pl[k-lb+1]=1;
                j=ne[j];
            }
        }

        dp[0]=1;
        for(register int j=1;j<=la;++j){
            if(pl[j-lb+1]&&j>=lb)dp[j]=(dp[j-lb]+dp[j-1])%mod;
            else{
                dp[j]=dp[j-1]%mod;
            }
        }
        printf("Case #%d: %lld
",i,dp[la]);
    }
}