Submission #564941

#	Time	Username	Problem	Language	Result	Execution time	Memory
564941		ac2hu	Palindromes (APIO14_palindrome)	C++14	47 / 100	1090 ms	68804 KiB

palindrome

#include <bits/stdc++.h>
#ifdef DEBUG
#include "../templates/debug.h"
#else 
#define deb(x...)
#endif
using namespace std;
const int C = 26;
struct node{
    int child[C];
    int cnt = 0;
    int dist = 0;
};
node root1[(int)3e5], root2[(int)3e5];
int r1 = 1, r2 = 1;
void make_node_r1(int id, int d){
    for(int i = 0;i<C;i++){
        root1[id].child[i] = 0;
    }
    root1[id].cnt = 0;
    root1[id].dist = d;
}
void make_node_r2(int id, int d){
    for(int i = 0;i<C;i++){
        root2[id].child[i] = 0;
    }
    root2[id].cnt = 0;
    root2[id].dist = d;
}
string s;
int ans = 1;
auto is_pali(int l,int r){
    if(l > r)return true;
    if(s[l] != s[r])return false;
    return is_pali(l + 1, r - 1);
}
void add1(int l,int r){
    int val = 1;
    for(int i = l;i<=r;i++){
        int c = s[i] - 'a';
        if(!root1[val].child[c]){
            root1[val].child[c] = ++r1;
            make_node_r1(root1[val].child[c], root1[val].dist + 2);
        }
        val= root1[val].child[c];
        ++root1[val].cnt;
        deb(ans);
        ans = max(ans, root1[val].cnt*root1[val].dist);
    }
}
void add2(int l,int r){
    int val = 1;
    for(int i = l;i<=r;i++){
        int c = s[i] - 'a';
        if(!root2[val].child[c]){
            root2[val].child[c] = ++r2;
            make_node_r2(root2[val].child[c], root2[val].dist + 2);
        }
        val= root2[val].child[c];
        ++root2[val].cnt;
        ans = max(ans, root2[val].cnt*root2[val].dist);
    }
}
signed main(){
    make_node_r1(1,-1);
    make_node_r2(1,0);
    cin >> s;
    int n = s.size();
    vector<int> leq(n,0);
    vector<int> req(n,0);
    for(int i = 1;i<n;i++){
        if(s[i] == s[i - 1])leq[i] = 1 + leq[i - 1];
    }
    for(int i = n - 2;i>=0;i--){
        if(s[i] == s[i + 1])req[i] = 1 + req[i + 1];
    }
    for(int i = 0;i<n;i++){
        auto check = [&](int mid)->bool{
            if(i - mid < 0)return false;
            if(i + mid > n - 1)return false;
            return is_pali(i - mid, i + mid);
        };
        int l = min(leq[i], req[i]) + 1,r = n;
        while(l<r){
            int mid = (l + r + 1)/2;
            if(check(mid)){
                l = mid;
            }
            else
                r = mid - 1;
        }
        if(check(l)){
            add1(i,i + l);
        }
        if(i > 0 && s[i] == s[i - 1]){
            l = min(leq[i - 1], req[i]) + 1,r = n - 1;
            while(l < r){
                int mid = (l + r + 1)/2;
                if(i - 1 - mid >= 0 && i + mid < n && is_pali(i - 1 - mid, i + mid)){
                    l = mid;
                }
                else
                    r = mid - 1;
            }
            if(i - 1 - l >=0 && i + l < n && is_pali(i - 1 - l,i + l)){
                add2(i,i + l);
            }
        }
    }
    // deb(ans);
    vector<vector<int>> temp(26);
    for(int i = 0;i<n;i++){
        temp[s[i] - 'a'].push_back(req[i] + 1);
    }
    for(int j = 0;j<26;j++){
        vector<int> cc(n + 2, 0);
        for(auto e : temp[j]){
            cc[e + 1]--;
            cc[0]++;
        }
        for(int i = 1;i<=n + 1;i++)cc[i] += cc[i - 1];
        for(int i = 0;i<=n;i++){
            ans = max(ans, cc[i]*i);
        }
    }
    cout << ans << "\n";
}

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 0 / 26
• Subtask 5: 0 / 27