【HDU 3613】Best Reward

【题目链接】

点击打开链接

【算法】

正反两遍EXKMP，即可

【代码】

#include<bits/stdc++.h>
using namespace std;
#define MAXC 26
#define MAXL 500010

int T,ans,tmp,i,len;
int a[MAXC+],Next[MAXL],extend1[MAXL],extend2[MAXL],sum[MAXL];
char s1[MAXL],s2[MAXL];

template <typename T> inline void read(T &x) {
        int f = ; x = ;
        char c = getchar();
        for (; !isdigit(c); c = getchar()) { if (c == '-') f = -f; }
        for (; isdigit(c); c = getchar()) x = (x << ) + (x << ) + c - '';
        x *= f;
}
template <typename T> inline void write(T x) {
    if (x < ) { putchar('-'); x = -x; }
    if (x > ) write(x/);
    putchar(x%+'');
}
template <typename T> inline void writeln(T x) {
    write(x);
    puts("");
}
inline void exkmp(char *s1,char *s2,int *Next,int *Extend) {
        int i=,j,pos;
        while (i +  < len && s2[i+] == s2[i]) i++;
        Next[] = i;
        pos = ;
        for (i = ; i < len; i++) {
                if (i + Next[i-pos] < pos + Next[pos]) Next[i] = Next[i-pos];
                else {
                        j = pos + Next[i-pos] - i;
                        if (j < ) j = ;
                        while (i + j < len && s2[j] == s2[i+j]) j++;
                        Next[i] = j;
                        pos = i;
                }
        }
        i = ;
        while (i < len && s1[i] == s2[i]) i++;
        Extend[] = i;
        pos = ;
        for (i = ; i < len; i++) {
                if (i + Next[i-pos] < pos + Extend[pos]) Extend[i] = Next[i-pos];
                else {
                        j = pos + Extend[pos] - i;
                        if (j < ) j = ;
                        while (i + j < len && s1[i+j] == s2[j]) j++;
                        Extend[i] = j;
                        pos = i;
                }
        }
}

int main() {

        read(T);
        while (T--) {
                for (i = ; i <= MAXC; i++) read(a[i]);
                scanf("%s",s1);
                len = strlen(s1);
                sum[] = a[s1[]-'a'+];
                for (i = ; i < len; i++) {
                        s2[len-i-] = s1[i];
                        if (i > ) sum[i] = sum[i-] + a[s1[i]-'a'+];
                }
                exkmp(s2,s1,Next,extend1);
                exkmp(s1,s2,Next,extend2);
                ans = ;
                for (i = ; i < len - ; i++) {
                        tmp = ;
                        if (extend1[len-i-] == i + ) tmp += sum[i];
                        if (extend2[i+] == len - i - ) tmp += sum[len-] - sum[i];
                        ans = max(ans,tmp);
                }
                writeln(ans);
        }

        return ;

}