# |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
900616 |
2024-01-08T16:22:45 Z |
LCJLY |
Torrent (COI16_torrent) |
C++14 |
|
284 ms |
29936 KB |
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << " " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << " " << j << " " << #i << " " << q << " " << #p << endl;
#define show4(x,y) for(auto it:x) cout << it << " "; cout << #y << endl;
typedef pair<long long,long long>pii;
typedef pair<pii,pii>pi2;
int n,a,b;
vector<int>adj[300005];
int pp[300005];
void dfs(int index, int par){
for(auto it:adj[index]){
if(it==par) continue;
pp[it]=index;
dfs(it,index);
}
}
int best=INT_MAX;
pii edge; //ban edge
int dp(int index, int par){
int hold=0;
vector<int>child;
for(auto it:adj[index]){
if(it==par) continue;
if(it==edge.first&&index==edge.second) continue;
if(it==edge.second&&index==edge.first) continue;
child.push_back(dp(it,index));
}
sort(child.begin(),child.end());
reverse(child.begin(),child.end());
for(int x=0;x<(int)child.size();x++){
hold=max(hold,child[x]+x+1);
}
return hold;
}
void solve(){
cin >> n >> a >> b;
int temp,temp2;
for(int x=0;x<n-1;x++){
cin >> temp >> temp2;
adj[temp].push_back(temp2);
adj[temp2].push_back(temp);
}
dfs(a,-1);
int cur=b;
vector<int>v;
while(1){
v.push_back(cur);
if(cur==a) break;
cur=pp[cur];
}
int l=0;
int r=v.size()-2;
int mid;
while(l<=r){
mid=(l+r)/2;
edge.first=v[mid];
edge.second=v[mid+1];
int hold=dp(a,-1);
int hold2=dp(b,-1);
best=min(best,max(hold,hold2));
if(hold2>hold){
r=mid-1;
}
else l=mid+1;
}
cout << best;
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int t=1;
//cin >> t;
while(t--){
solve();
}
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3 ms |
7512 KB |
Output is correct |
2 |
Correct |
2 ms |
7516 KB |
Output is correct |
3 |
Correct |
2 ms |
7516 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
278 ms |
27056 KB |
Output is correct |
2 |
Correct |
284 ms |
28224 KB |
Output is correct |
3 |
Correct |
245 ms |
29388 KB |
Output is correct |
4 |
Correct |
251 ms |
28884 KB |
Output is correct |
5 |
Correct |
240 ms |
26380 KB |
Output is correct |
6 |
Correct |
247 ms |
27132 KB |
Output is correct |
7 |
Correct |
260 ms |
29936 KB |
Output is correct |