Submission #773037

#	Time	Username	Problem	Language	Result	Execution time	Memory
773037		davitmarg	Power Plant (JOI20_power)	C++17	47 / 100	1461 ms	39200 KiB

power

/*
DavitMarg
In pr honky-tonk,
Down in Mexico
*/
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <cstring>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <queue>
#include <bitset>
#include <stack>
#include <cassert>
#include <iterator>
#include <random>
#include <chrono>
#define mod 1000000007ll
#define LL long long
#define LD long double
#define MP make_pair    
#define PB push_back
#define all(v) v.begin(), v.end()
#define fastIO ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
using namespace std;

const int N = 500005;

int n;
string s;
vector<int> g[N];
int dp[N];

int dfs(int v, int p, bool start = false)
{
    dp[v] = s[v] - '0';
    int sum = 0;
    int mx = 0;
    for(int i = 0; i < g[v].size(); i++)
    {
        int to = g[v][i];
        if(to == p)
            continue;
        sum += dfs(to, v);
        mx = max(dp[to], mx);
    }
    dp[v] = max(dp[v], sum - (s[v] - '0'));
    if(start)
        dp[v] = max(dp[v], (s[v] - '0') + mx);
    return dp[v];
}

LL myRand()
{
    return ((LL)rand() << 16) + rand();
}

void solve()
{
    cin >> n;
    for(int i = 1; i <= n - 1; i++)
    {
        int a, b;
        cin >> a >> b;
        g[a].PB(b);
        g[b].PB(a);
    }
    cin>>s;
    s = '#' + s;
    int ans = 0;

    vector<int> p;
    for(int i = 1; i <= n; i++)
    {
        if(s[i] == '1')
            p.PB(i);
        if(g[i].size() == 1)
        {
            p.PB(i);
            p.PB(i);
        }
    }

    srand(69);
    int k = 2000;

    if(n > 5000)
        k = 39;

    for(int i = 0; i < k; i++)
    {
        int v = p[myRand() % p.size()];
        ans = max(ans, dfs(v, -1, true));
    }
    cout<<ans<<endl;
}

int main()
{
    fastIO;
    int T = 1;
    //cin >> T;
    while (T--)
    {
        solve();
    }

    return 0;
}

/*


cd /mnt/d/Davit/Projects/VSCode; g++ -std=c++17 -O2 -Wall -Wextra -Ddeath -Wshadow source.cpp -o orz; ./orz; rm orz

*/

Compilation message (stderr)

power.cpp: In function 'int dfs(int, int, bool)':
power.cpp:45:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |     for(int i = 0; i < g[v].size(); i++)
      |                    ~~^~~~~~~~~~~~~

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