Submission #1005180

#TimeUsernameProblemLanguageResultExecution timeMemory
1005180emad234One-Way Streets (CEOI17_oneway)C++17
0 / 100
0 ms348 KiB
#include "bits/stdc++.h" #define F first #define S second #define ll long long #define pii pair<ll,ll> const ll mxN = 1e5 + 5; const ll mod = 1e9 + 7; using namespace std; struct edge{ int first,id,second; }; vector<vector<edge>>v,tr; int p[mxN]; int ans[mxN]; bool vis[mxN]; int dep[mxN]; void calctr(int u){ vis[u] = 1; for(auto x : v[u]){ if(vis[x.F]) continue; tr[x.F].push_back({u,x.id,!x.S}); tr[u].push_back(x); calctr(x.F); } } int n,m,pr; int g[mxN],t[mxN]; int ng,nt; void dfs(int u,int par,int ty,int id){ dep[u] = dep[par] + 1; for(auto x : tr[u]){ if(x.F == par) continue; dfs(x.F,u,x.S,x.id); } if(g[u]){ if(vis[g[u]]) nt--; else ng++; } if(t[u]){ if(vis[t[u]]) ng--; else nt++; } // cout<<nt<<' '<<ng<<'\n'; vis[u] = 1; if(p[u] == 0) p[u] = m; for(auto x : v[u]) if(x.F != par) p[u] = min(dep[x.F],p[u]); p[par] = p[u]; // cout<<u<<' '<<p[u]<<'\n'; if(p[u] >= dep[u]){ if(ng) ans[id] = ty + 1; else if(nt) ans[id] = (!ty) + 1; } } signed main(){ // ios_base::sync_with_stdio(0); // cin.tie(0); // cout.tie(0); cin >>n>>m; v.resize(n + 4); tr.resize(n + 4); for(int i = 1;i <= m;i++){ int x,y; cin >>x>>y; v[x].push_back({y,i, 0}); v[y].push_back({x,i, 1}); } cin >>pr; for(int i = 0;i < pr;i++){ int x,y; cin >>x>>y; g[x] = y; t[y] = x; } calctr(1); // cout<<"TEST\n"; memset(vis,0,sizeof vis); dfs(1,0,0,0); for(int i = 1;i <= m;i++) cout<<(ans[i] == 0 ? 'B' : (ans[i] == 2 ? 'R' : 'L')); }
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