Submission #614073

#	Time	Username	Problem	Language	Result	Execution time	Memory
614073		HediChehaidar	Power Plant (JOI20_power)	C++17	0 / 100	4 ms	5024 KiB

power

#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef double db;
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;} // greatest common divisor (PGCD)
ll lcm(ll a , ll b) {return (a * b) / gcd(a , b);} // least common multiple (PPCM)
#define ss second
#define ff first
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define vi vector<int>
#define vii vector<pair<int,int>>
#define vl vector<ll>
#define vll vector<pair<ll,ll>>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pdd  pair<double,double>
#define vdd  vector<pdd>
#define dte  tuple<double , double , double>
using namespace std;
const int INF = 1000*1000*1000; // 1 e 9
const int MOD = 1e9 + 7;//998244353 ;
const double EPS = 0.000000001; // 1 e -9
const ll inf = (ll)1e18;

int n;
vi adj[(int)2e5 + 10];
int p[(int)2e5 + 10];
int down[(int)2e5 + 10];

int s[(int)2e5 + 10];
int sub[(int)2e5 + 10];

int ans = 0;
void dfs2(int pos , int par){

}
void dfs(int pos , int par){
    sub[pos] = s[pos];
    for(auto c : adj[pos]){
        if(c != par){
            dfs(c , pos);
            sub[pos] += sub[c];
        }
    }
    if(sub[pos] == 1) {
        down[pos] = 1; return;
    }
    for(auto c : adj[pos]){
        if(c != par){
            if(s[pos] && sub[pos] == sub[c] + 1){
                ans = max(ans , down[c] + 1 );
            }
            down[pos] += down[c];
        }
    }
    if(s[pos]) down[pos]--;
}
int main(){
    //ifstream fin ("testing.txt");
    //ofstream fout ("output.txt");
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    cin>>n;
    if(n > 2020) return 0;
    for(int i = 0 ; i < n - 1 ; i++){
        int a , b; cin>>a>>b; adj[a].pb(b); adj[b].pb(a);
    }
    /*for(int i = 1 ; i <= n ; i++) {
        cout << i << " : "; for(auto c : adj[i]) cout << c << " ";
        cout << "\n";
    }*/
    string ch; cin>>ch; for(int i = 1 ; i <= n ; i++) s[i] = ch[i - 1] == '1';
    for(int i = 1 ; i <= n ; i++){
        for(int j = 1 ; j <= n ; j++){
            down[j] = sub[j] = 0;
        }
        dfs(i , 0);
        for(int j = 1 ; j <= n ; j++) ans = max(ans , down[j]);
        //if(i == 1) for(int j = 1 ; j <= n ; j++) cout << down[j] << " ";
        //cout << ans << "\n";
    }
    cout << ans << "\n";
    return 0;
}

/*
    Think of : BS / DFS / BFS / SSSP / SCC / MSP / MAX FLOW / TOPSORT / LCA / MATRIX / DP(bitmask) / 2 POINTERS / SEG TREE / MATH / UN FIND / MO / HLD
    Read the statement CAREFULLY !!
    Make a GREADY APPROACH !!!! (start from highest / lowest)
    Make your own TESTS !!
    Be careful from CORNER CASES !
*/

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 0 / 53