Submission #858992

#	Time	Username	Problem	Language	Result	Execution time	Memory
858992		VinhLuu	Palindromic Partitions (CEOI17_palindromic)	C++14	60 / 100	559 ms	131072 KiB

palindromic

#include <bits/stdc++.h>
#define ll long long
using namespace std;

const ll mod = 1e9 + 7;
const int Max = 1e6 + 5;
const ll dm = 998244353;

string s[Max];
int dp[Max],n;
ll lt[Max],hs[Max],t[Max],pw[Max];

int get(int i,int j){
    return (hs[j]%mod + mod - (1LL * hs[i - 1]*lt[j - i + 1])%mod)%mod;
}

int got(int i,int j){
    return (t[j]%dm + dm - (1LL * t[i - 1]*pw[j - i + 1])%dm)%dm;
}

int dfs(int i){
    if(dp[i] != 0) return dp[i];
    dp[i] = 1;
    int l = i, r = n - i + 1;
    if(l > r) return dp[i] = 0;
    if(l == r) return dp[i] = 1;
    int mid = (r - l + 1) / 2;
    for(int j = 1; j <= mid; j ++){
        if(get(l, l + j - 1) == get(r - j + 1, r) && got(l, l + j - 1) == got(r - j + 1, r)){
            dp[i] = max(dp[i], 2 + dfs(l + j));
        }
    }
    return dp[i];
}


void solve(int c){
    n = s[c].size();
    s[c] = " " + s[c];
    for(int i = 1; i <= n; i ++){
        dp[i] = 0;
        hs[i] = ((1LL * hs[i - 1] * 26)%mod + (int)(s[c][i] - 'a'))%mod;
        t[i] = ((1LL * t[i - 1] * 26)%dm + (int)(s[c][i] - 'a'))%dm;
    }
    cout << dfs(1) << "\n";
}

signed main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int tt; cin >> tt;
    int mx = 0;
    for(int i = 1; i <= tt; i ++){
        cin >> s[i];
        mx = max(mx,(int)s[i].size());
    }
    lt[0] = 1;
    pw[0] = 1;
    for(int i = 1; i <= mx; i ++) lt[i] = (1LL * lt[i-1] * 26)%mod, pw[i] = (1LL * pw[i - 1] * 26)%dm;
    for(int i = 1; i <= tt; i ++) solve(i);
}

• Subtask 1: 15 / 15
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 0 / 40