#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, low = lca(u, t);
int ant, w = u;
while (w != low)
{
for (auto v: grafo[w])
{
if (v.first == pai[w] || v.first == ant) continue;
if (!(mask&(1<<v.second)))
ans++;
}
ant = w;
w = pai[w], ans++;
}
if (t == low) return dp[mask][u][q] = ans;
ant = 0, w = t;
while (w != low)
{
for (auto v: grafo[w])
{
if (v.first == pai[w] || v.first == ant) continue;
if (!(mask&(1<<v.second)))
ans++;
}
ant = w;
w = pai[w], ans++;
}
return dp[mask][u][q] = ans;
}
int ans = 0;
if (q)
{
ans = solve(mask, u, 0);
for (int i = 0; i < n-1; i++)
if (!(mask&(1<<i)))
ans = min(ans, 1+solve(mask|(1<<i), u, 0));
return dp[mask][u][q] = ans;
}
for (auto v: grafo[u])
{
if (v.first == pai[u]) continue;
if ((mask&(1<<v.second))) continue;
ans = max(ans, solve(mask, 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:117:7: 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:122:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &u, &v);
~~~~~^~~~~~~~~~~~~~~~~
mousetrap.cpp: In function 'int solve(int, int, bool)':
mousetrap.cpp:60:27: warning: 'ant' may be used uninitialized in this function [-Wmaybe-uninitialized]
if (v.first == pai[w] || v.first == ant) continue;
~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
512 KB |
Output is correct |
2 |
Correct |
2 ms |
512 KB |
Output is correct |
3 |
Correct |
2 ms |
512 KB |
Output is correct |
4 |
Correct |
3 ms |
512 KB |
Output is correct |
5 |
Correct |
3 ms |
512 KB |
Output is correct |
6 |
Correct |
3 ms |
512 KB |
Output is correct |
7 |
Correct |
2 ms |
512 KB |
Output is correct |
8 |
Incorrect |
3 ms |
512 KB |
Output isn't correct |
9 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
8 ms |
1408 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 |
Correct |
3 ms |
512 KB |
Output is correct |
2 |
Correct |
2 ms |
512 KB |
Output is correct |
3 |
Correct |
2 ms |
512 KB |
Output is correct |
4 |
Correct |
3 ms |
512 KB |
Output is correct |
5 |
Correct |
3 ms |
512 KB |
Output is correct |
6 |
Correct |
3 ms |
512 KB |
Output is correct |
7 |
Correct |
2 ms |
512 KB |
Output is correct |
8 |
Incorrect |
3 ms |
512 KB |
Output isn't correct |
9 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
512 KB |
Output is correct |
2 |
Correct |
2 ms |
512 KB |
Output is correct |
3 |
Correct |
2 ms |
512 KB |
Output is correct |
4 |
Correct |
3 ms |
512 KB |
Output is correct |
5 |
Correct |
3 ms |
512 KB |
Output is correct |
6 |
Correct |
3 ms |
512 KB |
Output is correct |
7 |
Correct |
2 ms |
512 KB |
Output is correct |
8 |
Incorrect |
3 ms |
512 KB |
Output isn't correct |
9 |
Halted |
0 ms |
0 KB |
- |