Leetcode - path-sum
https://leetcode.com/problems/path-sum/
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.
Just think about the sum seems a bit difficult. It can be treated as if there is a path containing nodes and can be subbed by sum and then getting 0.
func hasPathSum(root *TreeNode, sum int) bool {
if root == nil {
return false
}
if root.Val == sum {
return true
}
return hasPathSum(root.Left, sum - root.Val) || hasPathSum(root.Right, sum - root.Val)
}
def has_path_sum(root, sum)
if root == nil
return false
end
if root.right == nil && root.left == nil && root.val == sum
return true
end
return has_path_sum(root.left, sum - root.val) || has_path_sum(root.right, sum - root.val)
end
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