Submission #1773089

---

Source Code Expand

#include <iostream>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>
#include <string>
#include <bitset>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <algorithm>
#include <sstream>
#include <stack>
#include <iomanip>
using namespace std;
#define pb push_back
#define mp make_pair
typedef pair<int,int> pii;
typedef long long ll;
typedef double ld;
typedef vector<int> vi;
#define fi first
#define se second
#define fe first
#define FO(x) {freopen(#x".in","r",stdin);freopen(#x".out","w",stdout);}
#define Edg int M=0,fst[SZ],vb[SZ],nxt[SZ];void ad_de(int a,int b){++M;nxt[M]=fst[a];fst[a]=M;vb[M]=b;}void adde(int a,int b){ad_de(a,b);ad_de(b,a);}
#define Edgc int M=0,fst[SZ],vb[SZ],nxt[SZ],vc[SZ];void ad_de(int a,int b,int c){++M;nxt[M]=fst[a];fst[a]=M;vb[M]=b;vc[M]=c;}void adde(int a,int b,int c){ad_de(a,b,c);ad_de(b,a,c);}
#define es(x,e) (int e=fst[x];e;e=nxt[e])
#define esb(x,e,b) (int e=fst[x],b=vb[e];e;e=nxt[e],b=vb[e])
int n;
queue<pii> q;
multiset<int> adj[233333];
map<pii,int> edg;
template<class T>
void ers(T&x,int g) {x.erase(x.find(g));}
int main()
{
	scanf("%d",&n);
	for(int i=1,a,b;i<=(n-1)*2;++i)
		scanf("%d%d",&a,&b),adj[a].insert(b),
		adj[b].insert(a),++edg[pii(min(a,b),max(a,b))];
	for(auto e:edg) if(e.se>=2) q.push(e.fi);
	int cnt=0;
	while(!q.empty())
	{
		pii x=q.front(); q.pop();
		if(edg[x]<2) continue;
		int a=x.fi,b=x.se;
		if(adj[a].size()<adj[b].size()) swap(a,b);
		edg[x]-=2; ++cnt;
		while(adj[a].find(b)!=adj[a].end())
			ers(adj[a],b);
		for(auto s:adj[b])
		{
			if(s==a) continue;
			int&pp=edg[pii(min(s,a),max(s,a))];
			++pp,--edg[pii(min(s,b),max(s,b))],
			ers(adj[s],b),adj[s].insert(a),adj[a].insert(s);
			if(pp>=2) q.push(pii(min(s,a),max(s,a)));
		}
		adj[b].clear();
	}
	if(cnt+1==n) puts("YES"); else puts("NO");
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:40:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
./Main.cpp:43:49: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   adj[b].insert(a),++edg[pii(min(a,b),max(a,b))];
                                                 ^

Judge Result