Submission #34117

#	Time	Username	Problem	Language	Result	Execution time	Memory
34117		wan2000	Palindromes (APIO14_palindrome)	C++14	100 / 100	89 ms	70580 KiB

palindrome

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N = 3e5+111;

int n;
string s;

struct node{
    int next[26];
    int len;
    ll num;
    int suflink;
    node(){
        memset(next,255,sizeof(next));
    }
};

node Tree[N];
int num, suf;
ll res;
vector<int> Adj[N];

void initTree(){
    num = suf = 2;
    Tree[1].len = -1; Tree[1].suflink = 1;
    Tree[2].len = 0; Tree[2].suflink = 1;
}

void addLetter(int p){
    int cur = suf, curlen = 0;
    int x = s[p]-'a';
    while(1){
        curlen = Tree[cur].len;
        if(p-curlen-1>=0&&s[p-curlen-1]==s[p]) break;
        cur = Tree[cur].suflink;
    }
    if(Tree[cur].next[x]!=-1){
        suf = Tree[cur].next[x];
        Tree[Tree[cur].next[x]].num++;
        return;
    }
    suf = ++num;
    Tree[num].len = Tree[cur].len + 2;
    Tree[cur].next[x] = num;
    Tree[num].num = 1;
    if(Tree[num].len==1){
        Tree[num].suflink = 2;
        Adj[2].push_back(num);
        return;
    }
    while(1){
        cur = Tree[cur].suflink;
        curlen = Tree[cur].len;
        if(p-curlen-1>=0&&s[p-curlen-1]==s[p]){
            Tree[num].suflink = Tree[cur].next[x];
            Adj[Tree[cur].next[x]].push_back(num);
            break;
        }
    }
    return;
}

void DFS(int u){
    for(auto v: Adj[u]){
        DFS(v);
        Tree[u].num += Tree[v].num;
    }
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin>>s;
    n = s.size();
    initTree();
    for(int i = 0; i < n; i++){
        addLetter(i);
    }
    DFS(1);
    DFS(2);
    for(int i = 3; i <= num; i++){
        res = max(res,(ll)Tree[i].num*Tree[i].len);
    }
    cout<<res<<'\n';
    return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 26 / 26
• Subtask 5: 27 / 27