#include <bits/stdc++.h>
using namespace std;
const int maxn = 11;
int n, t, m;
int pai[maxn], nivel[maxn];
int dp[1<<maxn][maxn][2];
vector<pair<int, int>> grafo[maxn];
void dfs(int u, int p)
{
for (auto pp: grafo[u])
{
int v = pp.first;
if (v == p) continue;
pai[v] = u, nivel[v] = nivel[u]+1;
dfs(v, u);
}
}
bool stuck(int mask, int u)
{
for (auto v: grafo[u])
if (v.first != pai[u] && !(mask&(1<<v.second))) return false;
return true;
}
int lca(int u, int v)
{
while (u != v)
{
if (nivel[u] > nivel[v]) u = pai[u];
else v = pai[v];
}
return u;
}
int solve(int mask, int u, bool q)
{
if (u == t) return 0;
if (dp[mask][u][q] != -1) return dp[mask][u][q];
if (stuck(mask, u))
{
int ans = 0;
while (true)
{
for (auto v: grafo[u])
if (v.first != pai[u] && !(mask&(1<<v.second)))
ans++;
if (u == lca(u, t))
{
if (u != m) ans++;
break;
}
ans++;
u = pai[u];
}
return dp[mask][u][q] = ans;
}
int ans = 0;
if (q) ans = solve(mask, u, 0);
for (auto v: grafo[u])
{
if (v.first == pai[u]) continue;
if ((mask&(1<<v.second))) continue;
if (q) ans = min(ans, 1+solve(mask|(1<<v.second), u, 0));
else ans = max(ans, solve(mask|(1<<v.second), v.first, 1));
}
return dp[mask][u][q] = ans;
}
int main(void)
{
scanf("%d %d %d", &n, &t, &m);
for (int i = 0; i < n-1; i++)
{
int u, v;
scanf("%d %d", &u, &v);
grafo[u].push_back({v, i});
grafo[v].push_back({u, i});
}
dfs(m, 0);
memset(dp, -1, sizeof dp);
printf("%d\n", solve(0, m, 1));
}
Compilation message
mousetrap.cpp: In function 'int main()':
mousetrap.cpp:89:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d %d", &n, &t, &m);
~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:94:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &u, &v);
~~~~~^~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
2 ms |
512 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
5 ms |
1536 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
2 ms |
512 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
2 ms |
512 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |