//Sylwia Sapkowska
#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;
void __print(int x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef LOCAL
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
#define int long long
typedef pair<int, int> T;
const int oo = 1e18, oo2 = 1e9+7, K = 30;
const int mod = 998244353;
void solve(){
int n, t, m;
cin >> n >> t >> m;
vector<vector<int>>g(n+1);
for (int i = 1; i<n; i++){
int a, b; cin >> a >> b;
g[a].emplace_back(b);
g[b].emplace_back(a);
}
vector<int>dp(n+1), par(n+1);
function<void(int, int)>dfs = [&](int v, int pa){
par[v] = pa;
int mx = 0, mx2 = 0;
for (auto x: g[v]){
if (x == pa) continue;
dfs(x, v);
if (dp[x] >= mx){
mx2 = mx;
mx = dp[x];
} else if (dp[x] >= mx2) {
mx2 = dp[x];
}
}
dp[v] = (int)g[v].size() - (v == t ? 0 : 1) + mx2;
};
dfs(t, t);
debug(dp);
int u = m;
vector<int>path(n+1);
while (1){
path[u] = 1;
if (u == par[u]) break;
u = par[u];
}
vector<int>deg(n+1);
for (int i = 1; i<=n; i++){
for (auto x: g[i]){
if (par[x] == i && !path[x]){
deg[i]++; //ile zbacza
}
}
}
auto check = [&](int mid){
int v = m;
int sum = 0;
while (1){
sum += deg[v];
if (v == par[v]) break;
v = par[v];
}
if (sum > mid) return false;
v = m;
int block = 0, need = 0;
while (1){
block++;
int dont_care = 0;
//rozwazyc zboczenie w dol w v
for (auto x: g[v]){
if (path[x]) continue;
if (dp[x] + sum > mid) need++;
else dont_care++;
}
sum -= dont_care; //slonik will win in mid moves anyway
if (block < need) return false;
if (v == par[v]) break;
v = par[v];
}
return true;
};
int L = 0, R = 2*n, ans = 2*n;
while (R >= L){
int mid = (L+R)/2;
if (check(mid)) {
ans = mid;
R = mid-1;
} else {
L = mid+1;
}
}
cout << ans << "\n";
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
while (t--) solve();
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
276 ms |
94160 KB |
Output is correct |
| 2 |
Correct |
252 ms |
84752 KB |
Output is correct |
| 3 |
Correct |
738 ms |
92504 KB |
Output is correct |
| 4 |
Correct |
338 ms |
46408 KB |
Output is correct |
| 5 |
Correct |
742 ms |
92428 KB |
Output is correct |
| 6 |
Correct |
730 ms |
92472 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
