Submission #1119326

#	Time	Username	Problem	Language	Result	Execution time	Memory
1119326		imarn	One-Way Streets (CEOI17_oneway)	C++14	0 / 100	16 ms	21840 KiB

oneway

#include<bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define plx pair<ll,int>
#define f first
#define s second
#define pb push_back
#define all(x) x.begin(),x.end()
#define szz(r) (ll)r.size()
#define vi vector<int>
#define vvi vector<vi>
#define pp pair<ll,int>
#define ub(x,i) upper_bound(all(x),i)-x.begin()
using namespace std;
const int mxn=3e5+5;
vector<pair<int,pii>>g[mxn],gr[mxn];
pii rd[mxn];
int ans[mxn]{0};
int di[mxn]{0},lo[mxn]{0},cur=0;
bool vis[mxn]{0};
int id[mxn]{0},cc=1;
stack<int>st;
vector<int>qr[mxn];
void dfs(int u,int rd){
    di[u]=lo[u]=++cur;vis[u]=1;
    st.push(u);
    for(auto [v,w]:g[u]){
        if(w.f==rd)continue;
        if(!di[v])dfs(v,w.f);
        if(vis[v])lo[u]=min(lo[u],lo[v]);
    }
    if(lo[u]==di[u]){
        while(st.top()!=u){
            int v=st.top();st.pop();
            id[v]=cc;vis[v]=0;
        }id[u]=cc;cc++;st.pop();vis[u]=0;
    }
}
int cn1=0,cn2=0;
bool vv[mxn]{0};
void solve(int u,int rd,int xo){
    vis[u]=1;
    for(auto [v,w]:gr[u]){
        if(vis[v])continue;
        solve(v,w.f,w.s);
    }
    for(auto it : qr[u]){
        if(it<0){
            if(vv[-it])cn1--,vv[-it]=0;
            else cn2++,vv[-it]=1;
        }
        else {
            if(vv[it])cn2--,vv[it]=0;
            else cn1++,vv[it]=1;
        }
    }
    if(rd==-1)return;
    if(cn1==0&&cn2==0)ans[rd]=2;
    else if(cn1>0)ans[rd]=xo;
    else if(cn2>0)ans[rd]=xo^1;

}
int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    int n,m;cin>>n>>m;
    for(int i=0;i<m;i++){
        cin>>rd[i].f>>rd[i].s;
        if(rd[i].f==rd[i].s){ans[i]=2;continue;}
        g[rd[i].f].pb({rd[i].s,{i,0}});g[rd[i].s].pb({rd[i].f,{i,1}});
    }
    for(int i=1;i<=n;i++){
        if(!di[i])dfs(i,-1);
    }
    for(int i=1;i<=n;i++){
        for(auto [v,w]:g[i]){
            if(id[i]==id[v])ans[w.f]=2;
            else gr[id[i]].pb({id[v],{w.f,w.s}}),gr[id[v]].pb({id[i],{w.f,w.s^1}});
        }
    }
    int p;cin>>p;
    for(int i=0;i<p;i++){
        int x,y;cin>>x>>y;
        if(id[x]==id[y])continue;
        qr[id[x]].pb(i+1);
        qr[id[y]].pb(-i-1);
    }memset(vis,0,sizeof vis);
    for(int i=1;i<cc;i++){
        if(!vis[i])solve(i,-1,-1);
    }
    for(int i=0;i<m;i++){
        if(ans[i]==2)cout<<'B';
        if(ans[i]==1)cout<<'R';
        if(ans[i]==0)cout<<'L';
    }
}

Compilation message (stderr)

oneway.cpp: In function 'void dfs(int, int)':
oneway.cpp:28:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   28 |     for(auto [v,w]:g[u]){
      |              ^
oneway.cpp: In function 'void solve(int, int, int)':
oneway.cpp:44:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   44 |     for(auto [v,w]:gr[u]){
      |              ^
oneway.cpp: In function 'int main()':
oneway.cpp:76:18: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   76 |         for(auto [v,w]:g[i]){
      |                  ^

• Subtask 1: 0 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40