Check-Tree-Traversal.py

def checktree(self, preorder, inorder, postorder, N): 
	
    	# if the array lengths are 0, then all of them are obviously equal 
    	if N == 0: 
    		return 1
    		
    	# if array lengths are 1, then check if all of them are equal 
    	if N == 1: 
    		return (preorder[0] == inorder[0]) and (inorder[0] == postorder[0]); 
    
    	# search for first element of preorder in inorder array 
    	idx = -1; 
    	
    	for i in range(N): 
    		if inorder[i] == preorder[0]: 
    			idx = i 
    			break
    	
    	if idx == -1: 
    		return 0;
    	
    	# matching element in postorder array
    	if preorder[0] != postorder[N-1]:
    	    return 0;
    	
    	# check for the left subtree 
    	ret1 = self.checktree(preorder[1:], inorder, postorder, idx); 
    	
    	# check for the right subtree	 
    	ret2 = self.checktree(preorder[idx + 1:], inorder[idx + 1:], 
    						postorder[idx:], N-idx-1); 
    	
    	# return 1 only if both of them are correct else 0 
    	return (ret1 and ret2)