Submission #947189

#	Time	Username	Problem	Language	Result	Execution time	Memory
947189		steveonalex	Palindromes (APIO14_palindrome)	C++14	100 / 100	82 ms	126804 KiB

palindrome

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ll mask){return __builtin_ctzll(mask);}
int logOf(ll mask){return 63 - __builtin_clzll(mask);}
 
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T& container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }
 
const long K = 26;
 
struct PalindromeTree{
    struct Node{
        long child[K], layer, pi;
        Node(long _layer = 0){
            memset(child, -1, sizeof child);
            layer = _layer;
            pi = -1;
        }
    };
 
    vector<Node> a;
    vector<int> visit_cnt;
 
    PalindromeTree(){
        a.push_back(Node(-1)); a.push_back(Node(0));
        visit_cnt.resize(3e5 + 69);
        a[1].pi = a[0].pi = 0;
    }
 
    void add_child(long &x, long layer){
        x = a.size();
        a.push_back(Node(layer));
    }
 
    void build(string s){
        long id = 0;
        s = "#" + s;
        for(long i = 1; i<s.size(); ++i){
            visit_cnt[id]++;
            long digit = s[i] - 'a';
            long j = id;
            while(j >= 0){
                if (s[i] == s[i - a[j].layer - 1]) break;
                j = a[j].pi;
            }
 
            if (a[j].child[digit] != -1) {
                id = a[j].child[digit];
                continue;
            }
 
            add_child(a[j].child[digit], a[j].layer + 2);
            long v = a[j].child[digit];
 
            if (a[v].layer == 1) j = 1;
            else if (a[v].layer == 2) j = a[0].child[digit];
            else{
                j = a[j].pi;
                while(j >= 0){
                    if (j == 0 || (s[i] == s[i - a[j].layer - 1])) break;
                    j = a[j].pi;
                }
                j = a[j].child[digit];
            }
            a[v].pi = j;
            id = v;
        }
        visit_cnt[id]++;
    }
};
 
const int N = 3e5 + 69;
vector<int> graph[N];
int depth[N];
int sum[N];
 
void dfs(int u, int p){
    for(int v: graph[u]) if (v != p){
        dfs(v, u);
        sum[u] += sum[v];
    }
}
 
int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
 
 
    string s; cin >> s;
 
    PalindromeTree palin;
    palin.build(s);
 
    for(int i = 0; i<palin.a.size(); ++i){
        depth[i] = palin.a[i].layer;
        sum[i] = palin.visit_cnt[i];
        if (i != 0) graph[palin.a[i].pi].push_back(i);
    }
 
    dfs(0, 0);
 
    ll ans = 0;
    for(int i = 0; i<palin.a.size(); ++i) maximize(ans, 1LL *depth[i] * sum[i]);
        cout << ans << "\n";
 
    return 0;
}

Compilation message (stderr)

palindrome.cpp: In member function 'void PalindromeTree::build(std::string)':
palindrome.cpp:76:26: warning: comparison of integer expressions of different signedness: 'long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   76 |         for(long i = 1; i<s.size(); ++i){
      |                         ~^~~~~~~~~
palindrome.cpp: In function 'int main()':
palindrome.cpp:131:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<PalindromeTree::Node>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  131 |     for(int i = 0; i<palin.a.size(); ++i){
      |                    ~^~~~~~~~~~~~~~~
palindrome.cpp:140:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<PalindromeTree::Node>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  140 |     for(int i = 0; i<palin.a.size(); ++i) maximize(ans, 1LL *depth[i] * sum[i]);
      |                    ~^~~~~~~~~~~~~~~

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