Submission #1273633

#	Time	Username	Problem	Language	Result	Execution time	Memory
1273633		zowi	One-Way Streets (CEOI17_oneway)	C++20	0 / 100	3 ms	836 KiB

oneway

#include<bits/stdc++.h>
using namespace std;

int pre[100005];
int post[100005];
vector<int> graf[100005];
vector<int> graf_s[100005];
int dok[100005];
int odw[100005];
int low[100005];
int p = 1;
int po = 1;
int g= 1;
int jump[100005][20];
int wag[100005];
int wag1[100005];
int wyn[100005];
int gr[100005];
map<pair<int,int>,int> k1;
map<pair<int,int>,pair<int,int>> k;
set<pair<int,int>> pls;

void dfs(int x,int po)
{
	////cout << x << endl;
	odw[x] = 1;
	pre[x] = p;
	p++;
	int malo = p-1;
	for(int i : graf[x])
	{
		if(po == i) continue;
		if(odw[i] == 0)
		{
			dok[i] = x;
			dfs(i,x);
			malo = min(low[i],malo);
		}
		else
		{
			malo = min(malo,pre[i]);
		}
	}
	low[x] = malo;
}

void dfs1(int x)
{
	odw[x] = 1;
	pre[x] = p;
	p++;
	for(int i : graf_s[x])
	{
		if(odw[i] == 0)
		{
			jump[i][0] = x;
			dfs1(i);
		}
	}
	post[x] = po;
	po++;
}

int lca(int x,int y)
{
	if(pre[x] <= pre[y] && post[x] >= post[y])
	{
		return x;
	}
	if(pre[x] >= pre[y] && post[x] <= post[y])
	{
		return y;
	}
	for(int i = 18;i >= 0;--i)
	{
		if(jump[x][i] == 0) continue;
		if(!(pre[jump[x][i]] <= pre[y] && post[jump[x][i]] >= post[y]))
		{
			x = jump[x][i];
		}
	}
	return jump[x][0];
}

void dfs2(int x)
{
	odw[x] = 1;
	for(int i : graf_s[x])
	{
		if(odw[i] == 0)
		{
			dfs2(i);
			wag[x] += wag[i];
 		}
	}
}
void dfs3(int x)
{
	odw[x] = 1;
	for(int i : graf_s[x])
	{
		if(odw[i] == 0)
		{
			dfs3(i);
			wag1[x] += wag1[i];
 		}
	}
}
void dfs4(int x,int y)
{
	odw[x] = 1;
	gr[x] = y;
	for(int i : graf[x])
	{
		if(odw[i] == 0 && low[i] != pre[i] && gr[i] == 0)
		{
			dfs4(i,y);
		}
		if(odw[i] == 0 && low[i] == pre[i])
		{
			g++;
			dfs4(i,g);
		}
	}
}


int main()
{
	ios_base::sync_with_stdio(0);
	int n,m,a,b,m1;
	cin >> n >> m;
	m1 = m;
	for(int i = 0;i < m;++i)
	{
		cin >> a >> b;
		graf[a].push_back(b);
		graf[b].push_back(a);
		k1[{min(a,b),max(a,b)}] = i;
		pls.insert({a,b});
	}
	for(int i = 1;i <= n;++i)
	{
		if(odw[i] == 0)
			dfs(i,-1);
	}
	/*for(int i = 1;i <= n;++i)
	{
		////cout << pre[i] << ' ';
	}
	////cout << endl;
	//////cout << "2137 ";
	for(int i = 1;i <= n;++i)
	{
		
		////cout << low[i] << ' ';
	}
	////cout << endl;*/
	for(int i = 1;i <= n;++i)
	{
		odw[i] = 0;
	}
	for(int i = 1;i <= n;++i)
	{
		if(odw[i] == 0)
			dfs4(i,g);
	}
	for(int i = 1;i <= n;++i)
	{
		
		////cout << gr[i] << ' ';
	}
	////cout << endl;
	for(int i = 1;i <= n;++i)
	{
		odw[i] = 0;
	}
	for(int i = 2;i <= n;++i)
	{
		if(gr[i] != gr[dok[i]])
		{
			k[{min(gr[i],gr[dok[i]]),max(gr[i],gr[dok[i]])}] = {min(i,dok[i]),max(i,dok[i])};
			graf_s[gr[i]].push_back(gr[dok[i]]);
			graf_s[gr[dok[i]]].push_back(gr[i]);
		}
	}
	for(int i = 1;i <= n;++i)
	{
		////cout << gr[i] << ':' << ' ';
		for(int j : graf_s[gr[i]])
		{
			////cout << j << ' ';
		}
		////cout << endl;
	}
	for(int i = 1;i <= n;++i)
	{
		if(odw[i] == 0)
			dfs1(i);
	}
	for(int i = 1;i <= 18;++i)
	{
		for(int j = 1;j <= n;++j)
		{
			jump[j][i] = jump[jump[j][i-1]][i-1];
		}
	}
	p = 1;
	for(int i = 1;i <= n;++i)
	{
		//////cout << post[i] << ' ';
	}
	//////cout << endl;
	cin >> m;
	for(int i = 1;i <= n;++i)
	{
		odw[i] = 0;
		//cout << jump[i][0] << ' ';
	}
	//cout << endl;
	for(int i = 0;i < m;++i)
	{
		cin >> a >> b;
		//cout << gr[a] << ' ' << gr[b] << ' ';
		//cout<< lca(gr[a],gr[b]) << endl;
		wag[gr[a]]++;
		wag1[gr[b]]++;
		wag[lca(gr[a],gr[b])]--;
		wag1[lca(gr[a],gr[b])]--;
	}
	for(int i = 1;i <= n;++i)
	{
		odw[i] = 0;
		////cout << gr[i] << ' ' << wag[gr[i]] << ' ' << wag1[gr[i]] << endl;
	}
	for(int i = 1;i <= n;++i)
	{
		if(odw[i] == 0)
			dfs2(i);
	}
	for(int i = 1;i <= n;++i)
	{
		odw[i] = 0;
	}
	for(int i = 1;i <= n;++i)
	{
		if(odw[i] == 0)
			dfs3(i);
	}
	for(int i = 2;i <= n;++i)
	{
		////////cout << wag[gr[i]] << ' ';
		if(wag[gr[i]] > 0 && dok[i] > 0)
		{
			if(gr[i] != gr[dok[i]])
			{
				//////cout << k[{min(gr[i],gr[dok[i]]),max(gr[i],gr[dok[i]])}].first << ' ' << k[{min(gr[i],gr[dok[i]]),max(gr[i],gr[dok[i]])}].second << endl;
				wyn[k1[k[{min(gr[i],gr[dok[i]]),max(gr[i],gr[dok[i]])}]]] = 1;
				if(pls.find({i,dok[i]}) == pls.end())
				{
					wyn[k1[k[{min(gr[i],gr[dok[i]]),max(gr[i],gr[dok[i]])}]]] = 2;
				}
			}
		}
	}
	for(int i = 2;i <= n;++i)
	{
		////////cout << wag1[gr[i]] << ' ';
		if(wag1[gr[i]] > 0 && dok[i] > 0)
		{
			if(gr[i] != gr[dok[i]])
			{
				//////cout << k[{min(gr[i],gr[dok[i]]),max(gr[i],gr[dok[i]])}].first << ' ' << k[{min(gr[i],gr[dok[i]]),max(gr[i],gr[dok[i]])}].second << endl;
				wyn[k1[k[{min(gr[i],gr[dok[i]]),max(gr[i],gr[dok[i]])}]]] = 2;
				if(pls.find({i,dok[i]}) == pls.end())
				{
					wyn[k1[k[{min(gr[i],gr[dok[i]]),max(gr[i],gr[dok[i]])}]]] = 1;
				}
			}
		}
	}
	for(int i = 0;i < m1;++i)
	{
		////////cout << wyn[i];
		if(wyn[i] == 0)
		{
			cout << 'B';
		}
		if(wyn[i] == 1)
		{
			cout << 'R';
		}
		if(wyn[i] == 2)
		{
			cout << 'L';
		}
	}
	
}

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