Path Sum III (Leetcode 437)

Problem Link: https://leetcode.com/problems/path-sum-iii/

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def pathSum(self, root: Optional[TreeNode], targetSum: int) -> int:
        
        self.ans=0
        def func(root,targetSum):
            
            if(root is None):
                return
            
            if(root.val==targetSum):
                self.ans+=1
            
            func(root.left,targetSum-root.val)
            func(root.right,targetSum-root.val)
    
        def recursion(root,targetSum):
            
            if(root is None):
                return
            
            # Inorder Traversal
            recursion(root.left,targetSum)
            func(root,targetSum)
            recursion(root.right,targetSum)
        
        recursion(root,targetSum)
        return self.ans