P2375 [NOI2014] 动物园

求num[i] ，表示1~i前缀 的合法子串个数（ 满足前后缀相等，且不重合

 

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#include <iostream> #include <cstring> using namespace std;  const int N =1e6+3 ,mod= 1e9+7;  #define int long long  char a[N];  int n,p[N];     void init(){     int i,j=0;     p[1]=0;     for(i=2;i<=n;i++){         while(j>0&&a[i]!=a[j+1]) j=p[j];         if(a[i]==a[j+1]) j++;         p[i]=j;     }  }  signed main(){     int i,j,tes;     cin>>tes;           while(tes--){         cin>>a+1; n=strlen(a+1);         init();         int ans=1;                   for(i=1;i<=n;i++){             int t=0;             for(j=i;j>0;){                 if(p[j]*2<=i) t++;                 j=p[j];             }             //printf("%d: %d\n",i,t);             ans*=t; ans%=mod;         }         cout<<ans<<endl;     }        }