Submission #167387

#	Time	Username	Problem	Language	Result	Execution time	Memory
167387		2fat2code	One-Way Streets (CEOI17_oneway)	C++14	100 / 100	130 ms	17728 KiB

oneway

#include <bits/stdc++.h>
#define ll long long
#define all(a) (a).begin(), (a).end()
//#pragma GCC optimize("O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define sz() size()
#define fr first
#define sc second
#define pb push_back
#define er erase
#define in insert
#define pi pair<int,int>
#define pii pair<pair<int,int>,int>
#define mp make_pair
//#define int long long
#define rc(s) return cout<<s,0
#define rcc(s) cout<<s,exit(0)
using namespace std;

const int mod=1e9+7;
const int modp=1999999973;
const int modx=998244353;

int n,m,k,height[100005],comp[100005],grad[100005],val[100005];
char ans[100005];
vector<pair<int,int>>edge,nod[100005];
vector<int>nod2[100005],bridge;

int DFS1(int node,int par,int cnt){
    height[node]=height[par]+1;
    int res=height[node];
    for(auto it:nod[node]){
        if(it.second!=cnt){
            int x=it.first;
            int y=it.second;
            if(height[x]){
                res=min(res,height[x]);
                ans[y]='B';
            }
            else res=min(res,DFS1(x,node,y));
        }
    }
    if(res<height[node]){
        ans[cnt]='B';
        nod2[par].push_back(node);
        nod2[node].push_back(par);
    }
    else if(cnt>=1) bridge.push_back(cnt);
    return res;
}

void DFS2(int node,int curr){
    comp[node]=curr;
    for(auto i:nod2[node]) if(comp[i]==0) DFS2(i,curr);
}

int DFS3(int node,int par,int cnt){
    height[node]=height[par]+1;
    for(auto it:nod[node]){
        if(it.first!=par){
            grad[node]+=DFS3(it.first,node,it.second);
        }
    }
    if(grad[node]==0) ans[cnt]='B';
    else if(grad[node]<0 ^ edge[cnt-1].fr==par) ans[cnt]='L';
    else ans[cnt]='R';
    return grad[node];
}

int32_t main(){
    ios_base::sync_with_stdio(false);cin.tie(0);cerr.tie(0);cout.tie(0);
    srand(chrono::steady_clock::now().time_since_epoch().count());
  //  ifstream cin("input.in");
    cin >> n >> m;
    for(int i=1;i<=m;i++){
        int x,y;
        cin >> x >> y;
        edge.push_back({x,y});
        nod[x].push_back({y,i});
        nod[y].push_back({x,i});
    }
    for(int i=1;i<=n;i++) if(!height[i]) DFS1(i,i,0);
    for(int i=1;i<=n;i++) if(comp[i]==0) DFS2(i,i);
    for(int i=1;i<=n;i++) nod[i].clear();
    for(auto i:bridge){
        edge[i-1].fr=comp[edge[i-1].fr];
        edge[i-1].sc=comp[edge[i-1].sc];
        int x=edge[i-1].fr;
        int y=edge[i-1].sc;
        nod[x].push_back({y,i});
        nod[y].push_back({x,i});
    }
    cin >> k;
    for(int i=1;i<=k;i++){
        int x,y;
        cin >> x >> y;
        x=comp[x];
        y=comp[y];
        grad[x]++;
        grad[y]--;
    }
    for(int i=1;i<=n;i++) height[i]=0;
    for(int i=1;i<=n;i++) if(height[i]==0) DFS3(i,i,0);
    for(int i=1;i<=m;i++) cout << ans[i] ;
    cout << '\n';
    return 0;
}

Compilation message (stderr)

oneway.cpp: In function 'int DFS3(int, int, int)':
oneway.cpp:66:23: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
     else if(grad[node]<0 ^ edge[cnt-1].fr==par) ans[cnt]='L';
             ~~~~~~~~~~^~

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