112_path_sum.md

112 - Path Sum

leetcode link

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

Note: A leaf is a node with no children.

Example:

Given the below binary tree and sum = 22,

      5
     / \
    4   8
   /   / \
  11  13  4
 /  \      \
7    2      1

return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.

Recursive solution

// 23/05/2020
bool hasPathSum(TreeNode* root, int sum, int s=0) {
    if (root == nullptr) return false;
    if(!root->left&& !root->right && s + root->val == sum)
        return true;
    if (hasPathSum(root->left, sum , s + root->val))
        return true;
    return hasPathSum(root->right, sum, s + root->val);
}