HDU 3613 Best Reward

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;

const int N=1e6+10;
const int INF=0x3f3f3f3f;

char S[N], s[N];
int r[N], a[30], sum[N], L[N], R[N], k; ///R数组标记接首位的回文串（下标是回文串长度），L数组标记接尾位的回文串

void Manacher()
{
    int i, mx, id = 0;

    for (i = 2; i < k; i++)
    {
        r[i] = 1;

        mx = r[id]+id;

        if (mx > i) r[i] = min(r[2*id-i], mx-i);

        while (s[i-r[i]] == s[i+r[i]]) r[i]++;

        if (mx < r[i]+i) id = i;

        if (r[i] == i) L[r[i]-1] = 1; ///因为r保存的是半径，如果半径等于i，那么肯定接首位
        if (r[i]+i == k) R[r[i]-1] = 1; ///r[i]+i是以i为中心的回文串的边界，如果等于k，则接尾位
    }
}

int main()
{
    int T, i, ls, ans, num;

    scanf("%d", &T);

    while (T--)
    {
        k = 2;

        memset(r, 0, sizeof(r));
        memset(sum, 0, sizeof(sum));
        memset(L, 0, sizeof(L));
        memset(R, 0, sizeof(R));

        for (i = 0; i < 26; i++)
            scanf("%d", &a[i]);
        scanf("%s", S);

        ls = strlen(S);

        for (i = 1; i <= ls; i++)
            sum[i] = sum[i-1] + a[S[i-1]-‘a‘]; ///先将价值之和保存下来

        s[0] = ‘$‘; s[1] = ‘#‘;
        for (i = 0; S[i] != ‘\0‘; i++)
        {
            s[k++] = S[i];
            s[k++] = ‘#‘;
        }

        Manacher();

        ans = a[S[0]-‘a‘];

        for (i = 1; i < ls; i++)
        {
            num = 0;

            if (L[i]) num = sum[i];
            if (R[ls-i]) num += (sum[ls]-sum[i]);

            ans = max(ans, num);
        }

        printf("%d\n", ans);
    }

    return 0;
}