Submission #959570

#	Time	Username	Problem	Language	Result	Execution time	Memory
959570		jacobtpl	Palindromes (APIO14_palindrome)	C++17	100 / 100	51 ms	65476 KiB

palindrome

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <unordered_map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <vector>
using namespace std;

#define ll long long
#define pb push_back
#define mp make_pair
#define INF 1100000000
#define INFLL 1000000000000000000ll
#define ii pair<int,int>
#define sz(x) (int)(x).size()
#define all(x) (x).begin(),(x).end()
#define M1 1000000007ll
#define M2 1000000009ll
#define UQ(x) (x).resize(distance((x).begin(), unique(all(x))))
#define rep(i,a,b) for (int i = (a); i < (b); i++)
template<typename T> bool ckmax(T& a, T const& b) {return b>a?a=b,1:0;}
template<typename T> bool ckmin(T& a, T const& b) {return b<a?a=b,1:0;}


using vi = vector<int>;

struct PalTree {
    static const int ASZ = 26;
    struct node {
        array<int,ASZ> to = array<int,ASZ>();
        int len, link, oc = 0; // # occurrences of pal
        // int slink = 0, diff = 0;
        array<int,2> seriesAns;
        node(int _len, int _link) : len(_len), link(_link) {}
    };
    string s = "@"; vector<array<int,2>> ans = {{0,INF}};
    vector<node> d = {{0,1},{-1,0}}; // dummy pals of len 0,-1
    int last = 1;
    int getLink(int v) {
        while (s[sz(s)-d[v].len-2] != s.back()) v = d[v].link;
        return v;
    }
    /*
    void updAns() { // serial path has O(log n) vertices
        ans.pb({INF,INF});
        for (int v = last; d[v].len > 0; v = d[v].slink) {
            d[v].seriesAns=ans[sz(s)-1-d[d[v].slink].len-d[v].diff];
            if (d[v].diff == d[d[v].link].diff) 
                rep(i,0,2) ckmin(d[v].seriesAns[i],
                            d[d[v].link].seriesAns[i]);
            // start of previous oc of link[v]=start of last oc of v
            rep(i,0,2) ckmin(ans.back()[i],d[v].seriesAns[i^1]+1);
        }
    }*/
    void addChar(char C) {
        s += C; int c = C-'a'; last = getLink(last);
        if (!d[last].to[c]) {
            d.emplace_back(d[last].len+2,d[getLink(d[last].link)].to[c]);
            d[last].to[c] = sz(d)-1;
            // auto& z = d.back(); z.diff = z.len-d[z.link].len;
            // z.slink = z.diff == d[z.link].diff ? d[z.link].slink : z.link;
        } // max suf with different dif
        last = d[last].to[c]; ++d[last].oc;
        // updAns();
    }
    void numOc() { for (int i=sz(d)-1;i>=2;i--) d[d[i].link].oc += d[i].oc; }
    ll solve() {
        numOc();
        ll ans = 0;
        for (auto &x:d) {
            ckmax(ans, (ll)x.len*(ll)x.oc);
        }
        return ans;
    }
};


int main() {
    cin.sync_with_stdio(0);
    cin.tie(0);
    string s;
    cin>>s;
    PalTree p;
    for (int i=0;i<sz(s);i++) {
        p.addChar(s[i]);
    }
    cout << p.solve() << '\n';
}
// int dp[maxn][2]; // dp(i,b) = min number of palindromes split with parity b

// int main() {
//     scanf("%s",t);
//     int l = strlen(t);
//     init();
//     for (int i = 0; i < l; i++) {
//         add_letter(t[i]-'a');
//         if (i == 0) {
//             dp[0][0] = INF;
//             dp[0][1] = 1;
//         } else {
            
//         }
//     }
//     printf("%s\n", t);
// }

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