hdu-3613 Best Reward (manacher算法)

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
using namespace std;

const int maxn = 500100;
char s[maxn];
char txt[maxn<<1];
int p[maxn<<1];
int sum[maxn<<1];
int len; int val = 0; int n;
int v[26];
int oo = 0x3f3f3f3f;

void make() {
    txt[0] = ‘$‘;
    int pos = 0;
    for(int i = 0; i < len; i++) {
        txt[++pos] = ‘#‘;
        txt[++pos] = s[i];
    }txt[++pos] = ‘#‘;
    n = len * 2 + 2;
    txt[n] = ‘\0‘;
}

int get(int id) {
    if(txt[id] >= ‘a‘ && txt[id] <= ‘z‘) {
        return v[txt[id] - ‘a‘];
    }
    return 0;
}


void solve() {
    int maxx = 0, id;
    for(int i = 1; i < n; i++) {
        if(i < maxx)
            p[i] = min(p[id * 2 - i], p[id] + id - i);
        else p[i] = 1;
        while(txt[i - p[i]] == txt[i + p[i]]) {
            if(i + p[i] > maxx) {
                maxx = i + p[i];
                id = i;
            }
            p[i]++;
        }
    }
    for(int i = 1; i < n; i++) sum[i] = sum[i - 1] + get(i);
    for(int i = 1; i < n; i++) p[i]--;
    int ans = -oo, tsum = 0;
    for(int i = 2; i < n - 1; i++) {
        tsum = 0;
        int l, r;
        int newl, newr;

        if(p[i]) {
            l = i - p[i];
            r = i + p[i];
        }
        else {
            l = i - 1, r = i + 1;
        }

        if(l != 1 && r != len * 2 + 1) {
            tsum = 0;
            l = 1;
            newl = r, newr = len * 2 + 1;
        }
        else if(l != 1 && r == len * 2 + 1) {
            newl = 1, newr = l;
            tsum = sum[r] - sum[l];
        }
        else if(l == 1 && r != len * 2 + 1) {
            newl = r, newr = len * 2 + 1;
            tsum = sum[r] - sum[l];
        }
        else {
            tsum = -oo;
        }

        int newmid = (newl + newr) / 2;
        //printf("check %d %d %d %d %d %d %d\n", l, r, newl, newr, tsum, ans, newmid);
        if(newmid - p[newmid] != 1 && newmid + p[newmid] != len * 2 + 1) {
            ans = max(ans, tsum);
            continue;
        }
        tsum += (sum[newr] - sum[newl]);
        ans = max(ans, tsum);
    }
    printf("%d\n", ans);
}

int main() {
    int t;
    scanf("%d", &t);
    while(t--) {
        for(int i = 0; i < 26; i++) scanf("%d", &v[i]);
        scanf("%s", s);
        memset(p, 0, sizeof(p));
        memset(sum, 0, sizeof(sum));
        len = strlen(s);
        make();
        solve();
    }    
}