#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define all(x) x.begin(), x.end()
#define fi first
#define se second
#define pb push_back
const int maxn5 = 1e6 + 10;
int tale, mo, dp[maxn5];
vector <int> adj[maxn5];
inline bool dfs(int v, int par){
int z = -1;
for(auto u : adj[v]) if(u != par){
bool re = dfs(u, v);
if(re){
z = u;
}
}
if(v == mo){
if(adj[v].size() == 1){
dp[v] = 0;
return true;
}
int mx = 0;
for(auto u : adj[v]) if(u != par){
dp[v] += dp[u];
mx = max(mx, dp[u]);
}
dp[v] = min(dp[v] - mx + 1, dp[v]);
return true;
}
if(v == tale){
dp[v] = dp[z];
return true;
}
if(z == -1){
int mx = 0;
for(auto u : adj[v]) if(u != par){
dp[v] += dp[u];
mx = max(mx, dp[u]);
}
dp[v] = min(dp[v] - mx + 1, dp[v]) + 1;
return false;
}
int mx = 0;
for(auto u : adj[v]) if(u != par){
dp[v] += dp[u];
if(z != u)
mx = max(mx, dp[u]);
}
dp[v] = min(dp[v] - mx + 1, dp[v]);
return true;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int n, a, b; cin >> n >> a >> b;
a--; b--;
for(int i = 0; i < n - 1; i++){
int a, b; cin >> a >> b;
a--; b--;
adj[a].pb(b);
adj[b].pb(a);
}
if(a == b)
return cout << 0 << endl, 0;
mo = b;
tale = a;
dfs(a, -1);
cout << dp[a] << endl;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
13 ms |
23764 KB |
Output is correct |
2 |
Correct |
13 ms |
23764 KB |
Output is correct |
3 |
Correct |
13 ms |
23816 KB |
Output is correct |
4 |
Correct |
14 ms |
23764 KB |
Output is correct |
5 |
Incorrect |
12 ms |
23756 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
293 ms |
72336 KB |
Output is correct |
2 |
Correct |
288 ms |
67384 KB |
Output is correct |
3 |
Incorrect |
697 ms |
73216 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
13 ms |
23764 KB |
Output is correct |
2 |
Correct |
13 ms |
23764 KB |
Output is correct |
3 |
Correct |
13 ms |
23816 KB |
Output is correct |
4 |
Correct |
14 ms |
23764 KB |
Output is correct |
5 |
Incorrect |
12 ms |
23756 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
13 ms |
23764 KB |
Output is correct |
2 |
Correct |
13 ms |
23764 KB |
Output is correct |
3 |
Correct |
13 ms |
23816 KB |
Output is correct |
4 |
Correct |
14 ms |
23764 KB |
Output is correct |
5 |
Incorrect |
12 ms |
23756 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |