#include <bits/stdc++.h>
#include "grader.h"
#ifndef EVAL
#include "grader.cpp"
#endif
#define pb push_back
#define ff first
#define ss second
#define sz(x) (int)x.size()
#define pii pair<int, int>
using namespace std;
const int NN = 600;
vector<pii> edges[NN];
vector<int> vv[NN];
int nn, used[NN];
void dfs(int u, int p = -1){
//if(ok) cout<<u<<" ";
vv[u].pb(u);
for(auto x:edges[u]){
if(x.ff == p || used[x.ss]) continue;
dfs(x.ff, u);
for(auto xx:vv[x.ff]) vv[u].pb(xx);
}
}
/*
13
1 2
1 5
1 6
2 3
2 4
1 7
7 8
7 9
8 10
8 11
9 12
9 13
5
1 3 5 9 13
6
1 2
1 3
1 4
1 5
1 6
6
1 2 3 4 5 6
16
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
10 11
11 12
12 13
13 14
14 15
15 16
16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
*/
int dfs_cc(int u, int p = -1){
pii mx = {-1, -1};
for(auto x:edges[u]){
if(used[x.ss] || x.ff == p) continue;
if(sz(vv[x.ff]) > mx.ff) mx.ff = sz(vv[x.ff]), mx.ss = x.ff;
}
if(mx.ff * 2 >= nn) return dfs_cc(mx.ss, u);
return u;
}
int solve(int cur){
for(int i=0;i<NN;i++) vv[i].clear();
dfs(cur);
int centr = dfs_cc(cur);
for(int i=0;i<NN;i++) vv[i].clear();
dfs(centr);
vector<pair<int, pii>> childs;
for(auto x:edges[centr]) if(!used[x.ss]) childs.pb({sz(vv[x.ff]), x});
sort(childs.begin(), childs.end());
vector<int> qq = vv[childs.back().ss.ff];
qq.pb(centr);
vector<int> uu(NN, 0);
uu[childs.back().ss.ss] = 1;
childs.pop_back();
int last = -1, nw = -1;
int start;
for(auto x:childs){
last = sz(qq);
nw = x.ff + last;
if(abs(nw*2 - nn) <= abs(nn - last*2)){
for(auto xx : vv[x.ss.ff]) qq.pb(xx);
}else { start = x.ss.ff; break; }
uu[x.ss.ss] = 1;
}
for(auto &x:qq) x += 1;
int res = query(qq);
if(res){
for(auto x:edges[centr]){
if(uu[x.ss]) continue;
else used[x.ss] = 1;
}
nn = sz(qq);
if(nn == 2){
if(query({qq.back()})) return qq.back()-1;
else { qq.pop_back(); return qq.back()-1; }
}
if(nn == 1) return centr;
return solve(centr);
}
else{
for(auto x:edges[centr]){
if(uu[x.ss]) used[x.ss] = 1;
}
nn = (nn - sz(qq));
if(nn == 1) return start;
nn++;
return solve(centr);
}
}
int findEgg (int N, vector < pair < int, int > > bridges){
memset(used, 0, sizeof used);
for(int i=0;i<=NN;i++) edges[i].clear(), vv[i].clear();
nn = N;
for(int i=0;i<sz(bridges);i++){
edges[bridges[i].ff-1].pb({bridges[i].ss-1, i});
edges[bridges[i].ss-1].pb({bridges[i].ff-1, i});
}
//nn = N;
//dfs(0);
return solve(0)+1;
}
Compilation message
eastereggs.cpp: In function 'int solve(int)':
eastereggs.cpp:143:22: warning: 'start' may be used uninitialized in this function [-Wmaybe-uninitialized]
143 | if(nn == 1) return start;
| ^~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
1 ms |
492 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
2 ms |
876 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
4 ms |
2028 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
