| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 76446 |
2018-09-13T14:11:29 Z |
MrTEK |
Torrent (COI16_torrent) |
C++14 |
|
408 ms |
23184 KB |
#include <bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
#define len(a) (int)a.size()
#define fi first
#define sc second
#define d1(w) cerr<<#w<<":"<<w<<endl;
#define d2(w,c) cerr<<#w<<":"<<w<<" "<<#c<<":"<<c<<endl;
#define d3(w,c,z) cerr<<#w<<":"<<w<<" "<<#c<<":"<<c<<" "<<#z<<":"<<z<<endl;
#define left ind+ind
#define right ind+ind+1
#define mid (l+r)/2
#define FAST_IO ios_base::sync_with_stdio(false);
#define endl '\n'
#define bit __builtin_popcount
typedef long long int ll;
const int maxn = 620;
const long long LINF = 1e18;
const int LOG = 31;
const int INF = 1e9;
const int P = 31;
const int N = 3e5 + 5;
const int M = 1e6 + 5;
const int SQ = 350;
const int MOD = 1e9 + 7;
typedef long long int lli;
typedef pair<int,int> pii;
vector <pii> ed[N],path;
int n,a,b,vis[N],vis2[N],id,h[N],ans = INF;
int solve(int cur,int back) {
vector <int> v;
for (auto i : ed[cur])
if (i.fi != back && h[i.sc] == 0)
v.pb(solve(i.fi,cur));
sort(v.begin(),v.end(),greater<int>());
int re = 0,cnt = 0;
for (auto i : v)
re = max(re,(++cnt) + i);
return re;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
// freopen(".gir","r",stdin);
// freopen(".cik","w",stdout);
cin >> n >> a >> b;
for (int i = 1 ; i < n ; i++) {
int u,v;
cin >> u >> v;
ed[u].pb(mp(v,++id));
ed[v].pb(mp(u,++id));
}
queue <pair< pair <int,int>,int> > Q;
Q.push(mp(mp(a,-1),-1));
while(len(Q)) {
auto temp = Q.front();
Q.pop();
if (vis[temp.fi.fi]) continue;
vis[temp.fi.fi] = temp.fi.sc;
vis2[temp.fi.fi] = temp.sc;
if (temp.fi.fi == b) {
int x = b;
while(x != -1) {
path.pb(mp(x,vis2[x]));
x = vis[x];
}
break;
}
for (auto i : ed[temp.fi.fi]) {
Q.push(mp(mp(i.fi,temp.fi.fi),i.sc));
}
}
reverse(path.begin(),path.end());
int l = 1, r = len(path);
while(l < r) {
auto i = path[mid];
if (i.sc % 2 == 0)
h[i.sc] = h[i.sc - 1] = 1;
else
h[i.sc] = h[i.sc + 1] = 1;
int ta = solve(a,-1);
int tb = solve(b,-1);
ans = min(ans,max(ta,tb));
if (ta <= tb)
l = mid + 1;
else
r = mid;
if (i.sc % 2 == 0)
h[i.sc] = h[i.sc - 1] = 0;
else
h[i.sc] = h[i.sc + 1] = 0;
}
auto i = path[l];
if (i.sc % 2 == 0)
h[i.sc] = h[i.sc - 1] = 1;
else
h[i.sc] = h[i.sc + 1] = 1;
ans = min(ans,max(solve(a,-1),solve(b,-1)));
if (i.sc % 2 == 0)
h[i.sc] = h[i.sc - 1] = 0;
else
h[i.sc] = h[i.sc + 1] = 0;
cout << ans << endl;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
9 ms |
7416 KB |
Output is correct |
| 2 |
Correct |
9 ms |
7548 KB |
Output is correct |
| 3 |
Correct |
8 ms |
7608 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
408 ms |
23184 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
