manacher+hash寻找k共同回文串个数(模板)

题目链接

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cassert>
#include <ctime>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
using namespace std;
using ll = long long ;
using ull = unsigned long long int ;
#define rep(i,a,b)  for(int i = a; i <= b;i++)
#define nrep(i,a,b) for(int i = a; i >= b; i--)
template<typename Tp = int>
Tp read() {
    Tp ans = 0; bool flag = true;
    char ch = getchar();
    while(!isdigit(ch)) {
        if(ch == '-') flag = false ;
        ch=getchar();
    }
    while(isdigit(ch)) {
        ans = (ans<<3)+(ans<<1)+(ch^48) ;
        ch = getchar();
    }
    return flag?ans:-ans ;
}
template<ll P,ll mod>
struct HASH {
    vector<ll>u,p;
    HASH(string &s):u(s.size()+2),p(s.size()+2){
        u[0]=1;
        p[0]=1;
        p[0]=s[0];
        for(int i=1;i<s.size();i++){
            u[i]=u[i-1]*P;
            p[i]=p[i-1]*P+s[i];
            if(u[i]>=mod)u[i]%=mod;
            if(p[i]>=mod)p[i]%=mod;
        }
    }
    ll get(int l,int r){
        return ((p[r]-p[l-1]*u[r-l+1]%mod)%mod+mod)%mod;
    }
};
const int N = 3e5+10 ;
char ss[N];
void solve() {
    int n=read();
    map<pair<ull,ull>,int>mp;
    for(int ii=0;ii<n;ii++){
        set<pair<ull,ull>>se;
        scanf("%s",ss+1);
        string s;
        s+="?#";
        for(int i=1;ss[i];i++){
            s+=ss[i];
            s+="#";
        }
        s+=".";
        vector<int>p(s.size(),0);
        HASH<131,998244353>ha1(s);
        HASH<1331,1000000007>ha2(s);
        for(int i=1,mid=0,r=0;i<s.size();i++){
            if(i<r) p[i]=min(r-i+1,p[2*mid-i]);
            else p[i]=1;
            while(s[i-p[i]]==s[i+p[i]]){
                if(s[i+p[i]]=='#'){
                    se.insert({ha1.get(i-p[i],i+p[i]),ha2.get(i-p[i],i+p[i])});
                }
                p[i]++;
            }
            if(i+p[i]-1>=r){
                mid=i;
                r=i+p[i]-1;
            }
        }
        for(auto &t:se)mp[t]++;
    }
    int ans=0;
    for(auto &[u,v]:mp){
        ans+=v==n;
    }
    printf("%d\n",ans);
}
int main()
{
#ifdef LOCAL
    freopen("1.in","r",stdin);
    freopen("1.out","w",stdout);
    time_t beg = clock();
#endif
    int t = 1;
    //t=read();
    while(t--){
        solve();
    }
    return 0;
}