<p>You have <code>n</code> binary tree nodes numbered from <code>0</code> to <code>n - 1</code> where node <code>i</code> has two children <code>leftChild[i]</code> and <code>rightChild[i]</code>, return <code>true</code> if and only if <strong>all</strong> the given nodes form <strong>exactly one</strong> valid binary tree.</p>

<p>If node <code>i</code> has no left child then <code>leftChild[i]</code> will equal <code>-1</code>, similarly for the right child.</p>

<p>Note that the nodes have no values and that we only use the node numbers in this problem.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/08/23/1503_ex1.png" style="width: 195px; height: 287px;" />
<pre>
<strong>Input:</strong> n = 4, leftChild = [1,-1,3,-1], rightChild = [2,-1,-1,-1]
<strong>Output:</strong> true
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/08/23/1503_ex2.png" style="width: 183px; height: 272px;" />
<pre>
<strong>Input:</strong> n = 4, leftChild = [1,-1,3,-1], rightChild = [2,3,-1,-1]
<strong>Output:</strong> false
</pre>

<p><strong class="example">Example 3:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/08/23/1503_ex3.png" style="width: 82px; height: 174px;" />
<pre>
<strong>Input:</strong> n = 2, leftChild = [1,0], rightChild = [-1,-1]
<strong>Output:</strong> false
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>n == leftChild.length == rightChild.length</code></li>
	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
	<li><code>-1 &lt;= leftChild[i], rightChild[i] &lt;= n - 1</code></li>
</ul>

// Legenda
#include<bits/stdc++.h>
using namespace std;
bool isPalindrome(string S)
{
    // Stores the reverse of the
    // string S
    string P = S;
 
    // Reverse the string P
    reverse(P.begin(), P.end());
 
    // If S is equal to P
    if (S == P) {
        // Return "Yes"
        return 0;
    }
    // Otherwise
    else {
        // return "No"
        return 1;
    }
}
// struct TreeNode {
//       int val;
//       TreeNode *left;
//       TreeNode *right;
//       TreeNode() : val(0), left(nullptr), right(nullptr) {}
//       TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
//       TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
//   };
class Solution {
public:
    bool validateBinaryTreeNodes(int n, vector<int>& leftChild, vector<int>& rightChild) {
        map<int ,int > mp;
            int flag = 1;
            int indeg[n];
            for(int i = 0;i<n;i++)indeg[i] = 0;
        for(int i = 0;i<n;i++){
          
            
              if(leftChild[i]!=-1){indeg[leftChild[i]]++;
            if(mp.find(leftChild[i]) != mp.end()){
                flag = 0;
                break;
            }
            else{
                mp[leftChild[i]] = i;
            }
              }
            if(rightChild[i]!=-1){indeg[rightChild[i]]++;
             if(mp.find(rightChild[i]) != mp.end()){
                flag = 0;
                break;
            }
            else{
                mp[rightChild[i]] = i;
            }
            }
        }
        cout<<flag<<endl;
        if(flag == 1){
            queue<int> q;
            int cnt=0;
            for(int i = 0;i<n;i++){
                if(indeg[i]==0)q.push(i);
            }
            if(q.size()>1)flag = 0;
            if(flag == 1){
                cnt = 0;
                while (!q.empty())
                {
                    int node = q.front();
                    cnt++;
                    q.pop();
                    if(leftChild[node]!=-1){
                        indeg[leftChild[node]]--;
                        if(indeg[leftChild[node]]==0){
                            q.push(leftChild[node]);
                        }
                    }
                    if(rightChild[node]!=-1){
                        indeg[rightChild[node]]--;
                        if(indeg[rightChild[node]]==0)
                        q.push(rightChild[node]);
                    }
                }
                if(cnt == n){
                    flag = 1;
                }
                else{
                    flag = 0;
                }
            }
        }
        if(flag)return true;
        else return false;
    }
};
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