# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1067732 | sleepntsheep | Torrent (COI16_torrent) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <cstdio>
#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;
}