제출 #887090

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
887090		phong	Palindromes (APIO14_palindrome)	C++17	47 / 100	1070 ms	131072 KiB

palindrome

#include<bits/stdc++.h>

#define ll long long
#define int long long
const int nmax = 1e6 + 5;
const ll oo = 1e18;
const int lg = 2;
const int base = 4000;
#define pii pair<int, int>
#define fi first
#define se second
#define debug(a, n) for(int i = 1; i <= n; ++i) cout << a[i] << ' ';
using namespace std;

const ll mod[] = {(ll)1e9 + 7, (ll)1e9 + 8277, (ll)1e9 + 8277, (ll)1e9+ 9277};

int n, cur = 0;
string s;
ll pw[nmax][lg], h[nmax][lg], rh[nmax][lg];

void Init(){
    for(int j = 0; j < lg; ++j) pw[0][j] = 1;
    for(int i = 1; i <= n; ++i){
        for(int j= 0; j < lg; ++j){
            pw[i][j] = pw[i - 1][j] * base % mod[j];
            h[i][j] = (h[i - 1][j] * base + s[i] - 'a' + 1) % mod[j];
        }
    }
    reverse(s.begin(), s.end());
    for(int i = 1; i <= n; ++i){
        for(int j = 0; j < lg; ++j){
            rh[i][j] = (rh[i - 1][j] * base + s[i] - 'a' + 1) % mod[j];
        }
    }

}
ll get(int l, int r, ll h[][lg], int j){
    return (h[r][j] - h[l - 1][j] * pw[r - l + 1][j] + mod[j] * mod[j]) % mod[j];
}

bool check(int l, int r){
    for(int j = 0; j < lg; ++j){
        if(get(l, r, h, j) != get(n - r + 1, n - l + 1, rh, j)) return 0;
    }
    return 1;
}
map<ll, ll> mp[lg], f, par, ind;
int cnt[nmax];

void update(int l, int r){
    bool ok = 1;
    while(l <= r){

        int x = get(l, r, h, 0);
        int y = get(l, r, h, 1);
        if(++mp[0][x] == 1 && ++mp[1][y] == 1){
            ind[x] = ++cur;
            if(ok){
                f[cur]++;
                ok = 0;
            }
            cnt[cur] = r - l + 1;
            if(l + 1 <= r - 1){
                par[x] = get(l + 1, r - 1, h, 0);

            }
        }
        else{
            if(ok){
                int id = ind[x];
                f[id]++;
            }
            break;
        }
        ++l, --r;
    }
}
vector<int> adj[nmax];
void dfs(int u){
    for(auto v : adj[u]){
        dfs(v);
        f[u] += f[v];
    }
}
main(){
    ios_base::sync_with_stdio(0);
//    cin.tie(0);cout.tie(0);
//    freopen("code.inp", "r", stdin);
//    freopen("code.out", "w", stdout);
    cin >> s;
    n = s.size(); s = ' ' + s + ' ';
    Init();
    for(int i = 1; i <= n; ++i){
        int l = 1, r = min(i, n - i + 1), kq = 1;
        while(l <= r){
            int mid = r + l >> 1;
            if(check(i - mid + 1, i + mid - 1)){
                kq = mid;
                l = mid + 1;
            }
            else r = mid - 1;
        }
        update(i - kq + 1, i + kq - 1);
        l = 1, r = min(i, n - i), kq = -1;
        while(l <= r){
            int mid = r + l >> 1;
            if(check(i - mid + 1, i + mid)){
                kq = mid;
                l = mid + 1;
            }
            else r = mid - 1;
        }
        if(kq != -1) update(i - kq + 1, i + kq);
    }
    for(auto [x, y] : mp[0]){
        int v = ind[x];
        int u = ind[par[x]];
        adj[u].push_back(v);
    }
    dfs(0);
    ll ans = 0;
    for(int i = 1; i <= cur; ++i){
        ans = max(ans, 1ll * f[i] * cnt[i]);
    }
    cout << ans;
}
/*

*/

컴파일 시 표준 에러 (stderr) 메시지

palindrome.cpp:85:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   85 | main(){
      | ^~~~
palindrome.cpp: In function 'int main()':
palindrome.cpp:96:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   96 |             int mid = r + l >> 1;
      |                       ~~^~~
palindrome.cpp:106:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  106 |             int mid = r + l >> 1;
      |                       ~~^~~

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