HDU3613 扩展KMP

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <queue>
#include <stack>
#include <deque>
#include <iostream>
using namespace std;
typedef long long LL;
const int MOD = 1000000007;
const int maxn = 40009 + 5;

int value[30];
int sum[500009], Next[500009], extend1[500009], extend2[500009];
char a[500009], b[500009];

void GetNext(char T[], int &m, int Next[])
{
    int a = 0, p = 0;
    Next[0] = m;

    for (int i = 1; i < m; i++)
    {
        if (i >= p || i + Next[i - a] >= p)
        {
            if (i >= p)
                p = i;

            while (p < m && T[p] == T[p - i])
                p++;

            Next[i] = p - i;
            a = i;
        }
        else
        {
            Next[i] = Next[i - a];
        }
    }
}

void GetExtend(char s[], int &n, char t[], int &m, int extend[], int Next[])
{
    int a = 0, p = 0;
    GetNext(t, m, Next);

    for (int i = 0; i < n; i++)
    {
        if (i >= p || i + Next[i - a] >= p)
        {
            if (i >= p)
            {
                p = i;
            }

            while (p < n && p - i < m && s[p] == t[p - i])
            {
                p++;
            }

            extend[i] = p - i;
            a = i;
        }
        else
        {
            extend[i] = Next[i - a];
        }
    }
}

int main()
{

    int mid1, mid2, head, k, i, j, t;

    scanf("%d", &t);
    while (t--)
    {
        for (i = 0; i < 26; i++)
            scanf("%d", &value[i]);

        scanf(" %s", a);
        k = strlen(a);

        sum[0] = value[a[0] - 'a'];
        for (i = 1; i < k; i++)
        {
            sum[i] = sum[i - 1] + value[a[i] - 'a'];
        }

        for (i = 0; i < k; i++)
            b[i] = a[k - 1 - i];

        GetExtend(a, k, b, k, extend1, Next);
        GetExtend(b, k, a, k, extend2, Next);
/*
        cout << "next:   ";
        for (int i = 0; i < k; i++)
            cout << Next[i] << " ";

        // 打印 extend
        cout << "
extend: ";
        for (int i = 0; i < k; i++)
            cout << extend[i] << " ";

        cout << endl
             << endl;
*/
        head = 0;
        for (i = 1; i < k - 1; i++)
        {
            if (extend1[i] == k - i)
            {
                mid2 = sum[k - 1] - sum[i - 1];
            }
            else
            {
                mid2 = 0;
            }

            if (k - i + extend2[k - i] == k)
            {
                mid1 = sum[i - 1];
            }
            else
            {
                mid1 = 0;
            }
        //    cout << i << " : " << mid1 << " " << mid2 << endl;
            if (mid1 + mid2 > head)
                head = mid1 + mid2;
        }
        printf("%d
", head);
    }

    return 0;
}