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Path Sum in Binary Tree

Certification: Basic Level Accuracy: 0% Submissions: 1 Points: 8

Write a Java program to determine if the binary tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

Example 1
    

  • Input:

      

    • root = [5,4,8,11,null,13,4,7,2,null,null,null,1]
      • 

    • targetSum = 22
      • 

    • 

  • Output: true
    • 

  • Explanation:

    Path Sum Binary Tree With Sum 22

    • 

    • There exists a root-to-leaf path 5 -> 4 -> 11 -> 2 with a sum of 22.
      • 

    •
Example 2
    

  • Input:

      

    • root = [1,2,3]
      • 

    • targetSum = 5
      • 

    • 

  • Output: false
    • 

  • Explanation:

    Path Sum Binary Tree With Sum 5

      

    • There does not exist a path that sums to 5.
      • 

    •
Constraints
    

  • The number of nodes in the tree is in the range [0, 5000].
    • 

  • -1000 ≤ Node.val ≤ 1000
    • 

  • -1000 ≤ targetSum ≤ 1000
    • 

  • Time Complexity: O(n), where n is the number of nodes in the tree.
    • 

  • Space Complexity: O(h), where h is the height of the tree.
    •
Binary TreeKPMGSwiggy
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Hint
Solution

Solution Hints

    
  
  • Use a recursive approach to traverse all root-to-leaf paths.
    • 
  
  • At each node, subtract the node's value from the target sum.
    • 
  
  • When reaching a leaf node, check if the remaining sum equals the leaf's value.
    • 
  
  • A leaf node is one with no children.
    • 
  
  • The path must end at a leaf node to be considered valid.
    •

Steps to solve by this approach:

 Step 1: Check if the tree is empty (root is null). If so, return false.
 Step 2: Check if the current node is a leaf node (no left or right children).
 Step 3: If it's a leaf node, check if its value equals the target sum.
 Step 4: If not a leaf node, subtract the current node's value from the target sum.
 Step 5: Recursively check if either the left or right subtree has a path with the remaining sum.
 Step 6: Return true if any path is found that satisfies the condition.
 Step 7: Return false if no valid path exists.

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