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Leetcode
Easy
Trees
Recursion
Strings
Binary Tree Paths

Return every root-to-leaf path in a binary tree as a string using -> between node values.

Acceptance 100%
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Problem Statement

Given the root of a binary tree, return all root-to-leaf paths in any order.

A root-to-leaf path is a path that starts at the root node and ends at a leaf node. Represent each path as a string by joining node values with ->.

This problem is mainly about traversing the tree while building the current path and recording it when a leaf is reached.

Input Format

  • The input is the root of a binary tree.
  • Each node contains an integer value.
  • The tree is provided in the usual binary-tree structure rather than as a single flat array.

Output Format

  • Return a list of strings.
  • Each string should represent one root-to-leaf path in the form root->...->leaf.
  • The order of paths does not matter.

Constraints

  • The tree has at least 1 node.
  • Node values may be positive, negative, or zero.
  • The tree can be skewed or balanced.
  • Use the path formatting exactly with -> between values.
Examples
Sample cases returned by the problem API.

Example 1

Input

root = [1,2,3,null,5]

Output

["1->2->5","1->3"]

Explanation

The root-to-leaf paths are 1->2->5 and 1->3.

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