1110 Complete Binary Tree

#include<iostream>
#include<vector>
#include<string>
#include<queue>
using namespace std;
struct Node{
	int id;
	int left;
	int right;
}node[21];
int getnum(string a){
	if(a=="-") return -1;
	else{
		if(a.length()==1) return (a[0]-'0');
		else{
			return ((a[0]-'0')*10+(a[1]-'0'));
		}
	}
}
bool judge1(int root){
	if(root==-1) return true;
	queue<int> q;
	q.push(root);
	bool shouldbeleaf=false;
	while(!q.empty()){
		int now=q.front();
		q.pop();
		if(node[now].left==-1&&node[now].right!=-1) return false;
		if(shouldbeleaf==true&&(node[now].left!=-1||node[now].right!=-1)) return false;
		if(node[now].left!=-1) q.push(node[now].left);
		if(node[now].right!=-1) q.push(node[now].right);
		else shouldbeleaf=true;
	}
}
vector<int> in;
void levetra(int root){
	queue<int> q;
	q.push(root);
	while(!q.empty()){
		int now=q.front();
		q.pop();
		in.push_back(now);
		if(node[now].left!=-1) q.push(node[now].left);
		if(node[now].right!=-1) q.push(node[now].right);
	}
}
int main()
{
	#ifndef ONLINE_JUDGE
	freopen("in.txt","r",stdin);
	#endif
	int n;
	cin>>n;
	for(int i=0;i<n;i++){
		string temp1,temp2;
		cin>>temp1>>temp2;
		int t1,t2;
		t1=getnum(temp1);
		t2=getnum(temp2);
		node[i].id=i;
		node[i].left=t1;
		node[i].right=t2;
	}
	int root;
	int flag[21]={};
	for(int i=0;i<n;i++){
		if(node[i].left!=-1) flag[node[i].left]=1;
		if(node[i].right!=-1) flag[node[i].right]=1;
	}
	for(int i=0;i<n;i++){
		if(flag[i]!=1){
			root=i;break;
		}
	}
	levetra(root);
	if(judge1(root)==true) cout<<"YES "<<in[n-1]<<endl;
	else cout<<"NO "<<in[0]<<endl;
	return 0;
}