Submission #1056390

#	Time	Username	Problem	Language	Result	Execution time	Memory
1056390		Zbyszek99	The Xana coup (BOI21_xanadu)	C++17	100 / 100	67 ms	23148 KiB

xanadu

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define size(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace std;
//mt19937 mt;void random(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll rand(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;

// DP[v][on/off][move];
ll DP[100001][2][2];
bool state[100001];
vector<int> graf[100001];

void dfs(int v, int pop)
{
    forall(it,graf[v])
    {
        if(it != pop) dfs(it,v);
    }
    // 0 0
    // cout << "xd\n";
    vector<ll> moves;
    ll sum = 0;
    forall(it,graf[v])
    {
        if(it != pop)
        {
            sum += DP[it][0][0];
            moves.pb(DP[it][0][1] - DP[it][0][0]);
        }
    }
    sort(all(moves));
    reverse(all(moves));
   // forall(it,moves) cout << it << " ";
   // cout << " moves\n";
    //cout << sum << " s1\n";
    if(state[v] == 1)
    {
        if(size(moves) == 0)
        {
            sum = 1e9;
        //  cout << "xd\n";
        }
        else
        {
            sum += moves[size(moves)-1];
            moves.pop_back();
        }
    }
   // cout << sum << " s2\n";
    //cout << sum << " xd\n";
    while(size(moves) > 1)
    {
        int end_ind = size(moves)-1;
        if(moves[end_ind] + moves[end_ind-1] <= 0)
        {
            sum += moves[end_ind] + moves[end_ind-1];
            moves.pop_back();
            moves.pop_back();
        }
        else break;
    }
    DP[v][0][0] = sum;
    // cout << "xd\n";
    // 1 0
    moves = {};
    sum = 0;
    forall(it,graf[v])
    {
        if(it != pop)
        {
            sum += DP[it][0][0];
      //      cout << DP[it][0][0] << " dp\n";
            moves.pb(DP[it][0][1] - DP[it][0][0]);
        }
    }
    //cout << sum << " sum\n";
    sort(all(moves));
    reverse(all(moves));
    if(state[v] == 0)
    {
        if(size(moves) == 0)
        {
            sum = 1e9;
        }
        else
        {
            sum += moves[size(moves)-1];
            moves.pop_back();
        }
    }
   // cout << sum << " s\n";
    while(size(moves) > 1)
    {
        int end_ind = size(moves)-1;
        if(moves[end_ind] + moves[end_ind-1] <= 0)
        {
            sum += moves[end_ind] + moves[end_ind-1];
            moves.pop_back();
            moves.pop_back();
        }
        else break;
    }
    DP[v][1][0] = sum;
    // cout << "xd\n";
    // 0 1
    moves = {};
    sum = 1;
    forall(it,graf[v])
    {
        if(it != pop)
        {
            sum += DP[it][1][0];
            moves.pb(DP[it][1][1] - DP[it][1][0]);
        }
    }
   // cout << "xd\n";
    sort(all(moves));
    reverse(all(moves));
    if(state[v] == 0)
    {
        if(size(moves) == 0)
        {
            sum = 1e9;
        }
        else
        {
            sum += moves[size(moves)-1];
            moves.pop_back();
        }
    }
    //cout << "xd\n";
    while(size(moves) > 1)
    {
        int end_ind = size(moves)-1;
        if(moves[end_ind] + moves[end_ind-1] <= 0)
        {
            sum += moves[end_ind] + moves[end_ind-1];
            moves.pop_back();
            moves.pop_back();
        }
        else break;
    }
    DP[v][0][1] = sum;
   //  cout << "xd\n";
    // 1 1
    moves = {};
    sum = 1;
    forall(it,graf[v])
    {
        if(it != pop)
        {
            sum += DP[it][1][0];
            moves.pb(DP[it][1][1] - DP[it][1][0]);
        }
    }
    sort(all(moves));
    reverse(all(moves));
    if(state[v] == 1)
    {
        if(size(moves) == 0)
        {
            sum = 1e9;
        }
        else
        {
            sum += moves[size(moves)-1];
            moves.pop_back();
        }
    }
    while(size(moves) > 1)
    {
        int end_ind = size(moves)-1;
        if(moves[end_ind] + moves[end_ind-1] <= 0)
        {
            sum += moves[end_ind] + moves[end_ind-1];
            moves.pop_back();
            moves.pop_back();
        }
        else break;
    }
    DP[v][1][1] = sum;
    // cout << "xd\n";;;;
    //cout << v << " " << DP[v][0][0] << " " << DP[v][0][1] << " " << DP[v][1][0] << " " << DP[v][1][1] << "dfs\n";
}

void solve()
{
    int n;
    cin >> n;
    rep(i,n-1)
    {
        int a,b;
        cin >> a >> b;
        graf[a].pb(b);
        graf[b].pb(a);
    }
    rep2(i,1,n) cin >> state[i];
    dfs(1,1);
    ll ans = min(DP[1][0][0],DP[1][0][1]);
    if(ans >= 1e9) cout << "impossible";
    else cout << ans;
}

int main()
{
    //ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //random();
    int t = 1;
  //  cin >> t;
    while(t--) solve();
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 10 / 10
• Subtask 4: 40 / 40
• Subtask 5: 30 / 30