Submission #556018

#	Time	Username	Problem	Language	Result	Execution time	Memory
556018		SavicS	Power Plant (JOI20_power)	C++17	0 / 100	3 ms	4948 KiB

power

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
 
using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;
typedef long double ld;
 
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pdd;
 
#define ff(i,a,b) for(int i = a; i <= b; i++)
#define fb(i,b,a) for(int i = b; i >= a; i--)
#define trav(a,x) for (auto& a : x)
 
#define sz(a) (int)(a).size()
#define pb push_back
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k)  print the k-th smallest number in os(0-based)

const int mod = 1000000007;
const int inf = 1e9 + 5;
const int mxN = 200005; 

int n;
string s;

vector<int> g[mxN];

bool ima[mxN];
void dfs1(int v, int p){
    ima[v] = (s[v] == '1');
    for(auto u : g[v]){
        if(u != p){
            dfs1(u, v);
            ima[v] |= ima[u];
        }
    }
}

int rez = 0;

int sad = 0;
void dfs2(int v, int p){

    int br = 0;
    for(auto u : g[v])if(u != p)br += ima[u];

    sad += br; sad -= (s[v] == '1'); rez = max(rez, sad);

    for(auto u : g[v]){
        if(u != p){
            sad -= ima[u];
            dfs2(u, v);
            sad += ima[u];
        }
    }

    sad -= br; sad += (s[v] == '1');

}

int main() {
    cin.tie(0)->sync_with_stdio(0);

    cin >> n;
    ff(i,1,n - 1){
        int u, v;
        cin >> u >> v;
        g[u].pb(v);
        g[v].pb(u);
    }

    cin >> s; s = ' ' + s;

    ff(root,1,n){
        dfs1(root, -1);
        dfs2(root, -1);
    }

    cout << rez << '\n';

    return 0;
}
/*
 
6
2 3
4 3
1 3
3 5
6 2
110011

8
1 2
3 5
6 4
4 5
5 2
7 2
2 8
11111111
 
16
7 10
5 11
9 4
14 12
2 11
14 16
4 2
1 13
11 3
7 1
15 9
2 1
11 6
14 9
8 9
0111111001001110

// probati bojenje sahovski
*/
 
 
 
 
 

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