/*
In the name of Allah
made by: Ahmed_Solyman
*/
#include <bits/stdc++.h>
#include <ext/rope>
using namespace std;
using namespace __gnu_cxx;
#pragma GCC optimize("-Ofast")
#pragma GCC optimize("-O1")
//-------------------------------------------------------------//
typedef long long ll;
typedef unsigned long long ull;
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define PI acos(-1)
#define lb lower_bound
#define ub upper_bound
#define endl '\n'
#define all(v) v.begin(),v.end()
#define allr(v) v.rbegin(),v.rend()
#define sum_to(n) (n*(n+1))/2
#define pb push_back
#define pf push_front
#define fil(arr,x) memset(arr,x,sizeof(arr))
const ll mod=1e9+7;
int dx[8]={0,1,0,-1,1,1,-1,-1};
int dy[8]={1,0,-1,0,1,-1,-1,1};
//-------------------------------------------------------------//
ll lcm(ll a,ll b)
{
return (max(a,b)/__gcd(a,b))*min(a,b);
}
void person_bool(bool x)
{
cout<<(x?"YES":"NO")<<endl;
}
const int N=1e5+5;
vector<int>adj[N],color(N);
ll n,dp[N][2][2];
ll solve(int i,int c,int rev,int p){
ll &ret=dp[i][c][rev];
if(~ret)return ret;
if(adj[i].size()==1 && i!=1){
if(c==1){
return ret=1e9;
}
else{
return ret=rev;
}
}
int opt=0;
bool flag=0;
ll sum=rev;
for(auto ch:adj[i]){
if(ch!=p){
ll a=solve(ch,rev^color[ch],0,i);
ll b=solve(ch,1^rev^color[ch],1,i);
sum+=min(a,b);
if(a==b){
flag=1;
}
else if(a>b){
++opt;
}
}
}
if(0){
ret=rev;
for(auto ch:adj[i]){
if(ch!=p){
ret+=min(solve(ch,rev^color[ch],0,i),solve(ch,1^rev^color[ch],1,i));
}
}
ret=min(ret,1000000000LL);
return ret;
}
else{
ret=1e9;
for(auto ch:adj[i]){
if(ch!=p){
ll a=solve(ch,rev^color[ch],0,i);
ll b=solve(ch,1^rev^color[ch],1,i);
int u=opt-(a>b);
if((c^u)==0){
ret=min(ret,sum-min(a,b)+a);
}
else{
ret=min(ret,sum-min(a,b)+b);
}
}
}
return ret;
}
}
int main()
{
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
#ifndef ONLINE_JUDGE
//freopen("input.in", "r", stdin);
//freopen("output.out", "w", stdout);
#endif
fast
fil(dp,-1);
int n;cin>>n;
for(int i=0;i<n-1;i++){
int u,v;cin>>u>>v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for(int i=1;i<=n;i++)cin>>color[i];
ll ans=min(solve(1,color[1],0,0),solve(1,!color[1],1,0));
if(ans>=1e9){
cout<<"impossible"<<endl;
}
else cout<<ans<<endl;
return 0;
}
Compilation message
xanadu.cpp: In function 'll solve(int, int, int, int)':
xanadu.cpp:53:7: warning: variable 'flag' set but not used [-Wunused-but-set-variable]
53 | bool flag=0;
| ^~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
6232 KB |
Output is correct |
| 2 |
Incorrect |
2 ms |
6236 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
6232 KB |
Output is correct |
| 2 |
Incorrect |
2 ms |
6236 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
42 ms |
20304 KB |
Output is correct |
| 2 |
Correct |
43 ms |
20048 KB |
Output is correct |
| 3 |
Correct |
51 ms |
20560 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
49 ms |
20304 KB |
Output is correct |
| 2 |
Correct |
43 ms |
19904 KB |
Output is correct |
| 3 |
Correct |
56 ms |
20452 KB |
Output is correct |
| 4 |
Correct |
37 ms |
9048 KB |
Output is correct |
| 5 |
Correct |
39 ms |
9304 KB |
Output is correct |
| 6 |
Correct |
41 ms |
9308 KB |
Output is correct |
| 7 |
Correct |
2 ms |
6260 KB |
Output is correct |
| 8 |
Correct |
15 ms |
7412 KB |
Output is correct |
| 9 |
Correct |
40 ms |
9368 KB |
Output is correct |
| 10 |
Correct |
57 ms |
9488 KB |
Output is correct |
| 11 |
Correct |
63 ms |
10128 KB |
Output is correct |
| 12 |
Correct |
46 ms |
10432 KB |
Output is correct |
| 13 |
Correct |
35 ms |
9052 KB |
Output is correct |
| 14 |
Correct |
38 ms |
9308 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
6232 KB |
Output is correct |
| 2 |
Incorrect |
2 ms |
6236 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
