#include <cstdio>
#include <numeric>
#include <algorithm>
#include <climits>
#include <vector>
using namespace std;
template <typename T>
using ve = vector<T>;
#define N 1005
int ans = INT_MAX;
int n, a, b, cb[N], dp[N], par[N];
ve<int> g[N], ab;
void dfs(int u, int p) {
par[u] = p;
for (auto v : g[u]) if (v != p) dfs(v, u);
}
void efs(int u, int p) {
dp[u] = 0;
ve<int> chdp;
for (auto v : g[u]) if (v != p) {
efs(v, u);
chdp.push_back(dp[v]);
}
sort(chdp.begin(), chdp.end(), greater<>());
for (int i = 0; i < (int)chdp.size(); ++i)
dp[u] = max(dp[u], chdp[i] + i + 1);
}
int main() {
scanf("%d%d%d", &n, &a, &b);
for (int u, v, i = 1; i < n; ++i) scanf("%d%d", &u, &v), g[u].push_back(v), g[v].push_back(u);
dfs(a, -1);
for (int c = par[b]; c != a; c = par[c]) ab.push_back(c);
reverse(ab.begin(), ab.end());
for (int c = b; c != a; c = par[c]) {
g[c].erase(find(g[c].begin(), g[c].end(), par[c]));
g[par[c]].erase(find(g[par[c]].begin(), g[par[c]].end(), c));
efs(a, -1);
efs(b, -1);
ans = min(ans, max(dp[a], dp[b]));
g[c].push_back(par[c]);
g[par[c]].push_back(c);
}
printf("%d\n", ans);
return 0;
}
Compilation message
torrent.cpp: In function 'int main()':
torrent.cpp:39:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
39 | scanf("%d%d%d", &n, &a, &b);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~
torrent.cpp:40:41: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
40 | for (int u, v, i = 1; i < n; ++i) scanf("%d%d", &u, &v), g[u].push_back(v), g[v].push_back(u);
| ~~~~~^~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
348 KB |
Output is correct |
| 2 |
Correct |
2 ms |
348 KB |
Output is correct |
| 3 |
Correct |
4 ms |
348 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
1 ms |
604 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
