Submission #1032808

#	Time	Username	Problem	Language	Result	Execution time	Memory
1032808		amine_aroua	One-Way Streets (CEOI17_oneway)	C++17	100 / 100	117 ms	15424 KiB

oneway

#include<bits/stdc++.h>
using namespace std;
vector<vector<pair<int , int>>> adj;
vector<int> depth;
vector<int> dp;
vector<int> pref;
vector<char> ans;
vector<pair<int ,int>> edges;
void dfs(int x)
{
    for(auto [u , i] : adj[x])
    {
        if(depth[u] == 0)
        {
            depth[u] = depth[x] + 1;
            dfs(u);
            dp[x]+=dp[u];
        }
        else if(depth[u] < depth[x])
        {
            dp[x]++;
        }
        else if(depth[u] > depth[x])
        {
            dp[x]--;
        }
    }
    dp[x]--;
}
void dfs1(int x)
{
    for(auto [u , i] : adj[x])
    {
        if(depth[u] == 0)
        {
            depth[u] = depth[x] + 1;
            dfs1(u);
            if(dp[u] == 0 && pref[u])
            {
                int m1 = (u == edges[i].first ? 1 : -1);
                int m2 = (pref[u] > 0 ? 1 : -1);
                if(m1 * m2 > 0)
                {
                    ans[i] = 'R';
                }
                else
                    ans[i] = 'L';
            }
            pref[x]+=pref[u];
        }
    }
}
int main()
{
    int n , m;
    cin>>n>>m;
    adj = vector<vector<pair<int, int>>> (n + 1);
    depth = vector<int> (n + 1);
    dp = depth;
    pref = depth;
    edges.assign(m , {});
    ans.assign(m , 'B');
    for(int i = 0 ; i < m; i++)
    {
        int x ,y;
        cin>>x>>y;
        edges[i] = {x , y};
        adj[x].push_back({y , i});
        adj[y].push_back({x , i});
    }
    for(int i = 1 ; i <= n ; i++)
    {
        if(depth[i] == 0)
        {
            depth[i] = 1;
            dfs(i);
        }
    }
    int p ;
    cin>>p;
    for(int i = 0 ; i < p ; i++)
    {
        int x , y;
        cin>>x>>y;
        pref[x]++;
        pref[y]--;
    }
    depth.assign(n + 1 , 0);
    for(int i = 1; i <= n ; i++)
    {
        if(depth[i] == 0)
        {
            depth[i] = 1;
            dfs1(i);
        }
    }
    for(int i = 0 ;i < m; i++)
        cout<<ans[i];
}

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