Why the no. of countNodes always returning as 1?

Question

In "exploreComponent" function count is increasing according to the no. of nodes present in that Component but before returning count decreases to 1, why this happening ?

Defined a Graph using matrix representation. Nodes are representated as nVertices. Firstly I made all the connection of nodes as 0 after adding edge between two nodes it is represented as 1 in adjMatrix.

class Graph:
    
    def __init__(self,nVertices):
        self.nVertices = nVertices
        self.adjMatrix = [[0 for i in range(nVertices)] for j in range(nVertices)]

    def addEdge(self,v1,v2):
        self.adjMatrix[v1][v2] = 1
        self.adjMatrix[v2][v1] = 1
    
    def containsEdge(self,v1,v2):
        return True if self.adjMatrix[v1][v2] > 0 else False

    def removeEdge(self,v1,v2):
        if self.containsEdge(v1,v2) is False:
            return
        self.adjMatrix[v1][v2] = 0
        self.adjMatrix[v2][v1] = 0

*# largest compenent*
    def largestComponent(self):
        visited = [False for i in range(self.nVertices)]
        largest = 0 
        for i in range(self.nVertices):
            if visited[i] is False:
                count = 0
                countNode = self.exploreComponent(i,visited,count)
            largest = max(countNode,largest)
    
        return largest

    *#helper function*
    def exploreComponent(self,node,visited,count):
        visited[node] = True
        count += 1
        print(count)

        for j in range(self.nVertices):
            if self.adjMatrix[node][j] > 0 and visited[j] is False:
                self.exploreComponent(j,visited,count)
        
        print("res",count)
        return count

*# creating graph*

g = Graph(9)
g.addEdge(0,1)
g.addEdge(0,2)
g.addEdge(1,2)
g.addEdge(2,3)
g.addEdge(4,5)
g.addEdge(6,7)
g.addEdge(7,8)

*# Function Calling*
res = g.largestComponent()
print(res)


Result:
1
2
3
4
res 4
res 3
res 2
res 1
1
2
res 2
res 1
1
2
3
res 3
res 2
res 1
1

Answer 1

The method exploreComponent is returning the incremented value of count. However when you invoke it, you are not storing the returned value anywhere

self.exploreComponent(j,visited,count)

( BTW you need to fix your question tags. Add the language ( python? ) and remove 'graph' since this is actually a question about graph theory )