Submission #712959

#	Time	Username	Problem	Language	Result	Execution time	Memory
712959		Victor	Palindromes (APIO14_palindrome)	C++17	100 / 100	27 ms	36064 KiB

palindrome

#include <bits/stdc++.h>
 
using namespace std;
 
#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define per(i, a, b) for (int i = b - 1; i >= (a); --i)
#define trav(a, x) for (auto &a : x)
 
#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
 
#define umap unordered_map
#define uset unordered_set
 
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef long long ll;
 
const int INF = 1000000007;

const int MAXN = 305000;

struct node {
    int next[26];
    int len;
    int sufflink;
    int num;
};

int len;
string s;
node tree[MAXN]; 
int num;            // node 1 - root with len -1, node 2 - root with len 0
int suff;           // max suffix palindrome
long long ans;

bool addLetter(int pos) {
    int cur = suff, curlen = 0;
    int let = s[pos] - 'a';

    while (true) {
        curlen = tree[cur].len;
        if (pos - 1 - curlen >= 0 && s[pos - 1 - curlen] == s[pos])     
            break;  
        cur = tree[cur].sufflink;
    }       
    if (tree[cur].next[let]) {  
        suff = tree[cur].next[let];
        return false;
    }

    num++;
    suff = num;
    tree[num].len = tree[cur].len + 2;
    tree[cur].next[let] = num;

    if (tree[num].len == 1) {
        tree[num].sufflink = 2;
        tree[num].num = 1;
        return true;
    }

    while (true) {
        cur = tree[cur].sufflink;
        curlen = tree[cur].len;
        if (pos - 1 - curlen >= 0 && s[pos - 1 - curlen] == s[pos]) {
            tree[num].sufflink = tree[cur].next[let];
            break;
        }       
    }           

    tree[num].num = 1 + tree[tree[num].sufflink].num;

    return true;
}

void initTree() {
    num = 2; suff = 2;
    tree[1].len = -1; tree[1].sufflink = 1;
    tree[2].len = 0; tree[2].sufflink = 1;
}

int main() {
    //assert(freopen("input.txt", "r", stdin));
    //assert(freopen("output.txt", "w", stdout));

  	int cnt[MAXN];
  	memset(cnt, 0, sizeof(cnt));
    cin>>s;
    len = sz(s);

    initTree();
	ll ans2 = 0;
    for (int i = 0; i < len; i++) {
        addLetter(i);
        ++cnt[suff];
    }

  	for(int i = num; i >= 2; i--){
        ans2 = max(ans2, tree[i].len * ll(cnt[i]));
        cnt[tree[i].sufflink] += cnt[i];
    }
  
    cout << ans2 << endl;

    return 0;
}

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