馬拉車存模板 求出每個迴文中心的迴文半徑 列舉端點 看兩邊是為迴文即可

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxn=1e6+10;

int book[maxn],pre[maxn];
char tmp[maxn],ch[maxn];
int l;

int solve(char *ch,int l)
{
    int i,p,r,res;
    memset(book,0,sizeof(book));
    p=0,r=0,res=0;
    for(i=0;i<l;i++)
    {
        if(i<r) book[i]=min(book[2*p-i],r-i);
        else book[i]=1;
        while(0<=i-book[i]&&i+book[i]<l&&ch[i-book[i]]==ch[i+book[i]]) book[i]++;
        res=max(res,book[i]);
        if(r<=i+book[i])
        {
            r=i+book[i];
            p=i;
        }
    }
    return res;
}

int main()
{
    int val[50];
    int t,i,j,ans,sum;
    scanf("%d",&t);
    while(t--)
    {
        for(i=0;i<26;i++) scanf("%d",&val[i]);
        scanf("%s",tmp);
        l=strlen(tmp);
        j=0;
        for(i=0;i<l;i++) ch[j++]='*',ch[j++]=tmp[i];
        ch[j++]='*',ch[j]='\0';
        l=j;

        for(i=0;i<l/2;i++)
        {
            pre[i]=val[tmp[i]-'a'];
            if(i>0) pre[i]+=pre[i-1];
        }
        solve(ch,l);
        ans=0;
        for(i=0;i+1<l/2;i++)
        {
            sum=0;
            if(book[i+1]-1==i+1) sum+=pre[i];
            if(book[i+1+l/2]-1==l/2-(i+1)) sum+=pre[l/2-1]-pre[i];
            ans=max(ans,sum);
        }
        printf("%d\n",ans);
    }
    return 0;
}