Routes from Root to Leaves

Easy

You are given the root of a binary tree. A leaf is a node with no children. For every leaf, write down the route from the root to it as a string: the node values in order, joined by an arrow -> with no spaces, such as "8->5->2". Return a list of all these strings, one per leaf. The strings may come in any order.

Example 1

root=tree_node([8, 3, 5, None, None, 2, 7]) → ['8->3', '8->5->2', '8->5->7']

The leaves are 3, 2 and 7. The routes to them are 8->3, 8->5->2 and 8->5->7.

Example 2

root=tree_node([-4, None, 6]) → ['-4->6']

The only leaf is 6, reached by -4->6.

Example 3

root=tree_node([12]) → ['12']

The root is itself a leaf, so the route is just one node.

Constraints

1 ≤ number of nodes ≤ 1000
-1000 ≤ Node.val ≤ 1000

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Topics

Tree Depth-First Search String Backtracking Binary Tree

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Input

root=tree_node([8, 3, 5, None, None, 2, 7])

Expected

['8->3', '8->5->2', '8->5->7']

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