Submission #948691

#TimeUsernameProblemLanguageResultExecution timeMemory
948691GrindMachineMousetrap (CEOI17_mousetrap)C++17
45 / 100
851 ms60364 KiB
#include <bits/stdc++.h> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> using namespace std; using namespace __gnu_pbds; template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>; typedef long long int ll; typedef long double ld; typedef pair<int,int> pii; typedef pair<ll,ll> pll; #define fastio ios_base::sync_with_stdio(false); cin.tie(NULL) #define pb push_back #define endl '\n' #define sz(a) (int)a.size() #define setbits(x) __builtin_popcountll(x) #define ff first #define ss second #define conts continue #define ceil2(x,y) ((x+y-1)/(y)) #define all(a) a.begin(), a.end() #define rall(a) a.rbegin(), a.rend() #define yes cout << "Yes" << endl #define no cout << "No" << endl #define rep(i,n) for(int i = 0; i < n; ++i) #define rep1(i,n) for(int i = 1; i <= n; ++i) #define rev(i,s,e) for(int i = s; i >= e; --i) #define trav(i,a) for(auto &i : a) template<typename T> void amin(T &a, T b) { a = min(a,b); } template<typename T> void amax(T &a, T b) { a = max(a,b); } #ifdef LOCAL #include "debug.h" #else #define debug(x) 42 #endif /* */ const int MOD = 1e9 + 7; const int N = 1e6 + 5; const int inf1 = int(1e9) + 5; const ll inf2 = ll(1e18) + 5; vector<int> adj[N]; vector<int> dp(N); void dfs1(int u, int p){ int deg = sz(adj[u])-(p != -1); dp[u] = deg; vector<int> vals; vals.pb(0), vals.pb(0); trav(v,adj[u]){ if(v == p) conts; dfs1(v,u); vals.pb(dp[v]); } sort(rall(vals)); dp[u] += vals[1]; } vector<int> curr_path; vector<int> path; void dfs2(int u, int p, int des){ curr_path.pb(u); if(u == des){ path = curr_path; } trav(v,adj[u]){ if(v == p) conts; dfs2(v,u,des); } curr_path.pop_back(); } void solve(int test_case) { int n,t,m; cin >> n >> t >> m; assert(m != t); rep1(i,n-1){ int u,v; cin >> u >> v; adj[u].pb(v), adj[v].pb(u); } dfs1(m,-1); dfs2(m,-1,t); vector<bool> on_path(n+5); trav(u,path) on_path[u] = 1; int moves = 0; int ans = 0; rep(i,sz(path)){ int u = path[i]; if(u == t) break; moves++; int to_block = sz(adj[u])-(u != m)-1; if(moves >= to_block){ ans += to_block; moves -= to_block; conts; } vector<int> vals; trav(v,adj[u]){ if(on_path[v]) conts; vals.pb(dp[v]); } sort(rall(vals)); assert(sz(vals) >= moves+1); ans += vals[moves]; for(int j = i; j < sz(path)-1; ++j){ int v = path[j]; int to_block_v = sz(adj[v])-(v != m)-1; ans += to_block_v; } break; } cout << ans << endl; } int main() { fastio; int t = 1; // cin >> t; rep1(i, t) { solve(i); } return 0; }
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