Getting run error on one test case in beautiful vertices

#1

You are given a graph with N vertices and M edges. Master parent is the vertex which has no parent but may have 0 or more children. In any connected component of the graph, vertex with the lowest value in that component serves as the master parent. A vertex is called beautiful if it has more children than its parent. Count the number of beautiful vertices in the given graph. The graph has no cycles or self loops.

Input Format
First line consists of two space separated integers denoting N and M and the following M lines consist of two space separated integers X and Y denoting there is an edge between vertices X and Y.

Constraints
1 <= N <= 100000 0 <= M <= N-1 1 <= x,y <= N

Output Format
Print the number of beautiful vertices in the graph.

Sample Input
4 3
1 2
2 3
2 4
Sample Output
1
Explanation
In this graph, we have vertices 1,2,3 and 4. Since 1 is the lowest among these, so it becomes the master vertex. Now, 1 has only 1 child while 2 has two children.So, 2 is a beautiful vertex. There are no more beautiful vertices in the graph.
My code for the above:

#2

Actually i didn’t get ur approach.
In this question do the following:

  1. Make a parent array which stores the parent of a particular vertex.
  2. Calculate the outdegrees of parent and child. If the outdegree of child is greater than parent then increment the ans.
  3. Return the ans.
#3

I used dsu to find the connected components and while taking union I took the condition that the set which had a higher value as root parent would be added to the set with lower root value.
After that I did a bfs for the elements which are master and all the elements in it’s connected component would have it’s parentnum(index of parent) and childnum(number of children ) updated .

#4

now also I am getting run error on one test case .(Using parent array)
sol:https://ide.codingblocks.com/s/270987