ACM-ICPC 2018 南京赛区网络预赛 I Skr (马拉车+hash去重)或(回文自动机/回文树)

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
#include <ctime>
#include <vector>
#include <queue>
#include <map>
#include <stack>
#include <set>
#include <bitset>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define ms(a, b) memset(a, b, sizeof(a))
#define pb push_back
#define mp make_pair
#define pii pair<int, int>
//#define eps 0.0000000001
#define IOS ios::sync_with_stdio(0);cin.tie(0);
#define random(a, b) rand()*rand()%(b-a+1)+a
#define pi acos(-1)
//const ll INF = 0x3f3f3f3f3f3f3f3fll;
const int inf = 0x3f3f3f3f;
const int maxn = 2e6 + 10;
const int maxm = 3000000 +10;
const int mod = 1000000007;

ull base=10007;
ull p[maxn<<1],has[maxn<<1];
ll pw[maxn<<1],sum[maxn<<1];
const int MOD=400007;
int head[maxn<<1],nxt[maxn<<1],cnt=0;
ull val[maxn];
bool exist(ull now){
    int u=now%MOD;
    for(int i=head[u];i;i=nxt[i]){
        if(val[i]==now) return true;
    }
    val[cnt]=now;
    nxt[cnt]=head[u];
    head[u]=cnt++;
    return false;
}
ull gethas(int l,int r){
    return has[r]-has[l-1]*p[r-l+1];
}
ll solve(int l,int r){
    ull tmp=gethas(l,r);
    if(exist(tmp)) return 0;
    ll ans=(sum[r]-sum[l-1]*pw[(r-l+1+1)/2]%mod+mod)%mod;
    return ans;
}
char s[maxn];
char Ma[maxn<<1];
int Mp[maxn<<1];
ll Manacher(char s[],int len){
    int l=0;
    Ma[l++]=‘$‘;
    Ma[l++]=‘#‘;
    for(int i=0;i<len;i++){
        Ma[l++]=s[i];
        Ma[l++]=‘#‘;
    }
    Ma[l]=0;
    pw[0]=p[0]=1;
    has[0]=sum[0]=0;
    for(int i=1;i<=l;i++){
        p[i]=p[i-1]*base;
        has[i]=has[i-1]*base+Ma[i];
        pw[i]=pw[i-1]*10%mod;
        if(Ma[i]>=‘0‘&&Ma[i]<=‘9‘){
            sum[i]=(sum[i-1]*10+Ma[i]-‘0‘)%mod;
        }else{
            sum[i]=sum[i-1];
        }
    }
    ll ans=0;
    int mx=0,id=0;
    for(int i=0;i<l;i++){
        if(Ma[i]!=‘#‘) ans=(ans+solve(i,i))%mod;
        Mp[i]=mx>i?min(Mp[2*id-i],mx-i):1;
        while(Ma[i+Mp[i]]==Ma[i-Mp[i]]){
            if(Ma[i+Mp[i]]!=‘#‘) ans=(ans+solve(i-Mp[i],i+Mp[i]))%mod;
            Mp[i]++;
        }
        if(mx<i+Mp[i]){
            mx=i+Mp[i];
            id=i;
        }
    }

    return ans;
}
int main() {
#ifdef LOCAL
    freopen("in.txt", "r", stdin);
//    freopen("input.txt", "w", stdout);
#endif
    scanf("%s",s);
    int len=strlen(s);
    printf("%lld\n",Manacher(s,len));
    return 0;
}