Count the string (KMP+DP)

题目链接

 #include <bits/stdc++.h>
 using namespace std;
 typedef long long ll;

 inline int read()
 {
     int x=,f=;char ch=getchar();
     while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}
     while(ch>=''&&ch<=''){x=x*+ch-'';ch=getchar();}
     return x*f;
 }

 /********************************************************************/

 const int maxn = 1e6+;
 char s[maxn];
 int Next[maxn];
 int sum[maxn];

 const int mod = ;

 int main(){
     int t; t = read();
     while(t--){
         int n; n = read();
         scanf("%s", s+);
         //int len = strlen(s+1);
         Next[] = ;;
         int k = ;
         for(int i = ;i <= n;i++){
             while(k >  && s[k+] != s[i]){
                 k = Next[k];
             }
             if(s[k+] == s[i])
                 k++;
             Next[i] = k;
         }
         int ans = ;
         memset(sum, , sizeof(sum));
         for(int i = ;i <= n;i++){
             sum[i] = (sum[Next[i]] + )%mod;
             ans = (ans + sum[i])%mod;
         }
         cout << ans << endl;
     }
     return ;
 }