#include <bits/stdc++.h> using namespace std; typedef long long ll; typedef pair<int, int> pii; typedef pair<ll, ll> pll; const int MAXN = 1e6; int N, R, X; vector<int> adj[MAXN+10]; int val[MAXN+10], dp[MAXN+10]; void dfs(int now, int bef, int p) { val[now]=p; int a=0, b=0, cnt=0; for(int nxt : adj[now]) { if(nxt==bef) continue; dfs(nxt, now, p+adj[nxt].size()-1); cnt++; if(a<=dp[nxt]) b=a, a=dp[nxt]; else if(b<=dp[nxt]) b=dp[nxt]; } dp[now]=b; if(cnt<=1) dp[now]=val[now]; //printf("%d : %d %d\n", now, val[now], dp[now]); } int main() { scanf("%d%d%d", &N, &R, &X); for(int i=1; i<N; i++) { int u, v; scanf("%d%d", &u, &v); adj[u].push_back(v); adj[v].push_back(u); } dfs(X, R, adj[X].size()); printf("%d\n", dp[X]-1); }

mousetrap.cpp: In function 'int main()':
mousetrap.cpp:35:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   35 |  scanf("%d%d%d", &N, &R, &X);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:39:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   39 |   scanf("%d%d", &u, &v);
      |   ~~~~~^~~~~~~~~~~~~~~~