#include <bits/stdc++.h>
#define ll long long
using namespace std;
#define pii pair<ll, ll>
ll oo = 2e9 + 9;
int n, m, k;
const int MAX = 2e5 + 5, MOD = 1e9 + 7, LOGMAX = 25;
vector<int> g[MAX];
int col[MAX];
ll dp[MAX][2][2];
void dfs(int node, int p){
dp[node][0][0] = oo;
dp[node][0][1] = oo;
dp[node][1][0] = oo;
dp[node][1][1] = oo;
ll sum = 0, sum2 = 0;
vector<ll> s = {0}, s2 = {0};
int p1 = 1, p2 = 1;
for(int to : g[node]){
if(p == to) continue;
dfs(to, node);
if(dp[to][0][0] < oo && dp[to][0][1] < oo){
sum += dp[to][0][0];
s.push_back(dp[to][0][1] - dp[to][0][0]);
}
else if(dp[to][0][0] < oo){
sum += dp[to][0][0];
}
else if(dp[to][0][1] < oo){
sum += dp[to][0][1];
p1 ^= 1;
}
else{
sum = oo;
}
if(dp[to][1][0] < oo && dp[to][1][1] < oo){
sum2 += dp[to][1][0];
s2.push_back(dp[to][1][1] - dp[to][1][0]);
}
else if(dp[to][1][0] < oo){
sum2 += dp[to][1][0];
}
else if(dp[to][1][1] < oo){
sum2 += dp[to][1][1];
p2 ^= 1;
}
else{
sum2 = oo;
}
}
sort(s.begin(), s.end());
sort(s2.begin(), s2.end());
ll pre = 0;
for(int i = 0; i < s.size(); i++){
pre += s[i];
if(i % 2 == p1){
dp[node][0][0] = min(sum + pre, dp[node][0][0]);
}
else{
dp[node][1][0] = min(sum + pre, dp[node][1][0]);
}
}
pre = 0;
for(int i = 0; i < s2.size(); i++){
pre += s2[i];
if(i % 2 == p2){
dp[node][1][1] = min(sum2 + pre, dp[node][1][1]);
}
else{
dp[node][0][1] = min(sum2 + pre, dp[node][0][1]);
}
}
dp[node][1][1]++;
dp[node][0][1]++;
if(!col[node]){
swap(dp[node][0][0], dp[node][1][0]);
swap(dp[node][0][1], dp[node][1][1]);
}
}
void solve(){
cin >> n;
for(int i = 1; i < n; i++){
int u, v; cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
for(int i = 1; i <= n; i++) cin >> col[i];
dfs(1, 1);
if(min(dp[1][0][0], dp[1][0][1]) > n){
cout << "impossible\n";
}
else{
cout << min(dp[1][0][0], dp[1][0][1]) << '\n';
}
}
signed main(){
int t = 1;
for(int i = 1; i <= t; i++){
solve();
}
}
Compilation message
xanadu.cpp: In function 'void dfs(int, int)':
xanadu.cpp:59:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
59 | for(int i = 0; i < s.size(); i++){
| ~~^~~~~~~~~~
xanadu.cpp:69:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
69 | for(int i = 0; i < s2.size(); i++){
| ~~^~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
7768 KB |
Output is correct |
2 |
Correct |
2 ms |
7772 KB |
Output is correct |
3 |
Correct |
2 ms |
7772 KB |
Output is correct |
4 |
Correct |
2 ms |
7772 KB |
Output is correct |
5 |
Correct |
2 ms |
7772 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
7768 KB |
Output is correct |
2 |
Correct |
2 ms |
7772 KB |
Output is correct |
3 |
Correct |
2 ms |
7772 KB |
Output is correct |
4 |
Correct |
2 ms |
7772 KB |
Output is correct |
5 |
Correct |
2 ms |
7772 KB |
Output is correct |
6 |
Correct |
2 ms |
7772 KB |
Output is correct |
7 |
Correct |
2 ms |
7772 KB |
Output is correct |
8 |
Correct |
2 ms |
7772 KB |
Output is correct |
9 |
Correct |
2 ms |
7768 KB |
Output is correct |
10 |
Correct |
2 ms |
7772 KB |
Output is correct |
11 |
Correct |
2 ms |
7772 KB |
Output is correct |
12 |
Incorrect |
2 ms |
7820 KB |
Output isn't correct |
13 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
99 ms |
41740 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
101 ms |
41688 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
7768 KB |
Output is correct |
2 |
Correct |
2 ms |
7772 KB |
Output is correct |
3 |
Correct |
2 ms |
7772 KB |
Output is correct |
4 |
Correct |
2 ms |
7772 KB |
Output is correct |
5 |
Correct |
2 ms |
7772 KB |
Output is correct |
6 |
Correct |
2 ms |
7772 KB |
Output is correct |
7 |
Correct |
2 ms |
7772 KB |
Output is correct |
8 |
Correct |
2 ms |
7772 KB |
Output is correct |
9 |
Correct |
2 ms |
7768 KB |
Output is correct |
10 |
Correct |
2 ms |
7772 KB |
Output is correct |
11 |
Correct |
2 ms |
7772 KB |
Output is correct |
12 |
Incorrect |
2 ms |
7820 KB |
Output isn't correct |
13 |
Halted |
0 ms |
0 KB |
- |