/*
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;
}
}
ret=1e9;
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(flag){
ret=0;
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;
}
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(1000000000LL,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:86:11: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
86 | if(c^u==0){
| ~^~~
xanadu.cpp: In function 'int main()':
xanadu.cpp:103:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
103 | freopen("input.in", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
xanadu.cpp:104:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
104 | freopen("output.out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
3 ms |
6236 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
3 ms |
6236 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
3 ms |
6232 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
6236 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
3 ms |
6236 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
