level-order

levelorder.cpp

#include<bits/stdc++.h>

using namespace std;

struct Node{
  int root, left, right;
  Node(int root=-1, int left=-1, int right=-1):root(root),left(left),right(right){ }
};

Node tree[11];

void makeEdge(int root, int left=-1, int right=-1){
  tree[root] = Node(root, left, right);
}

void level_order(int root){
	queue<int> q;
	q.push(root);
	while(!q.empty()){
		int qsize=q.size();
		while(qsize--){
			int now = q.front(); q.pop();
			cout << now << ' ';
			if(tree[now].left != -1)q.push(tree[now].left);
			if(tree[now].right != -1)q.push(tree[now].right);
		}
	}
}

int main(){
  //root of tree : 1
  //directed graph
  makeEdge(1, 2, 3);
  makeEdge(2, 4);
  makeEdge(3, 5, 6);
  makeEdge(5);
  makeEdge(6, -1, 7);
  makeEdge(4);
  makeEdge(7);
  
  //level-order 
  level_order(1);
}