Submission #1032906

#	Time	Username	Problem	Language	Result	Execution time	Memory
1032906		Malix	The Xana coup (BOI21_xanadu)	C++14	100 / 100	125 ms	20340 KiB

xanadu

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

typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> tii;
typedef vector<ll> li;
typedef vector<li> lii;

#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define LSOne(s) ((s)&(-s))

ll INF=1e18+10;
ll inf=1e9+10;
ll M=1e9+7;

int n;
vii a;
vector<vector<vector<ll>>> dp;
vi p,b;

void solve(int node){
    ll o1=inf,o2=inf,e1=0,e2=0;
    for(auto u:a[node]){
        if(p[node]==u)continue;
        p[u]=node;
        solve(u);
        ll o1t=min(o1+dp[0][1][u],e1+dp[1][1][u]);
        ll o2t=min(o2+dp[0][0][u],e2+dp[1][0][u]);
        ll e1t=min(e1+dp[0][1][u],o1+dp[1][1][u]);
        ll e2t=min(e2+dp[0][0][u],o2+dp[1][0][u]);
        o1=o1t;o2=o2t;e1=e1t;e2=e2t;
    }
    if(b[node]==0){
        dp[0][0][node]=e2;
        dp[1][0][node]=1+o1;
        dp[1][1][node]=1+e1;
        dp[0][1][node]=o2;
    }
    else{
        dp[0][0][node]=o2;
        dp[1][0][node]=1+e1;
        dp[1][1][node]=1+o1;
        dp[0][1][node]=e2;
    }
}

int main() {   
//ios::sync_with_stdio(0);
//cin.tie(0);
//freopen("test_input.txt", "r", stdin);
//freopen("test_output.txt", "w", stdout);
   cin>>n;
   a.resize(n);p.resize(n,-1);b.resize(n);
   dp.resize(2,vector<vector<ll>>(2,vector<ll>(n)));
   REP(i,0,n-1){
    int x,y;
    cin>>x>>y;
    x--;y--;
    a[x].PB(y);
    a[y].PB(x);
   }
   REP(i,0,n)cin>>b[i];
   solve(0);
   ll ans=min(dp[0][0][0],dp[1][0][0]);
   if(ans>=inf)cout<<"impossible";
   else cout<<ans;
}

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