Submission #3947

#	Time	Username	Problem	Language	Result	Execution time	Memory
3947		wurikiji	Cactus? Not cactus? (kriii1_C)	C++98	0 / 1	72 ms	11816 KiB

C

#include <vector>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <string>
#include <algorithm>
#include <stack>

using namespace std;

vector<int> node[100001];
vector<int> rv[100001];
bool chk[100001];
int group[100001];
int cnt[100001];
stack<int> st;

int ret;
int grp;
void dfs(int x)
{
	chk[x] = true;
	for(int i = 0 ;i < node[x].size();i++)
	{
		if( !chk[node[x][i]] ) 
			dfs(node[x][i]);
	}
	st.push(x);
}
void dfs2(int x)
{
	chk[x] = true;
	group[x] = grp;
	for(int i = 0 ;i < rv[x].size();i++)
	{

		if( !chk[rv[x][i]] ) {
			cnt[rv[x][i]]++;
			dfs2(rv[x][i]);
		}
		else if( group[rv[x][i]] == grp )
		{
			cnt[rv[x][i]]++;
		}
	}
}
int main(void){
	int n, m;

	scanf("%d %d",&n, &m);

	for(int i = 0 ;i < m ;i++)
	{
		int a, b;
		scanf("%d %d", &a, &b);
		node[a].push_back(b);
		rv[b].push_back(a);
	}

	memset(chk,0,sizeof(chk));
	for(int i = 1; i <= n;i++)
	{
		if( !chk[i] ) 
			dfs(i);
	}

	memset(cnt,0,sizeof(cnt));
	memset(group, 0, sizeof(group));
	memset(chk,0,sizeof(chk));

	grp = 0;
	while(!st.empty()){
		int next = st.top();
		st.pop();
		if(!chk[next])
		{
			dfs2(next);
			grp++;
		}
	}

	for(int i = 1 ;i <=n ;i++)
	{
		int count = 0;
		for(int j = 0 ;j < rv[i].size();j++)
		{
			if( group[rv[i][j]] == group[i] )
				count++;
		}
		if( count > 1 ) 
		{
			printf("Not cactus\n");
			return 0;
		}
	}

	printf("Cactus\n");
	return 0;
}

• Subtask 1: 0 / 1