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Path In Zigzag Labelled Binary Tree

MediumMathTree
Solve on LeetCode

Medium · linear scan solution for Path In Zigzag Labelled Binary Tree. Python, Go, and a step-by-step animation.

01

Problem

Read the prompt, flip through the examples, then steal the idea.

LeetCode 1104. Path In Zigzag Labelled Binary Tree. The copyrighted prompt is on LeetCode. This page is a working linear scan solution for this problem: editable input, Python, Go, and a step-by-step animation.

Constraints

  • —Player inputs are capped so the animation stays readable.
  • —Match LeetCode's own constraints when you submit there.

Examples

Input

nums =
[2, 1, 5, 3]

Output

5

A single pass keeps the running maximum. 5 wins.

02

Solution

Python and Go. The walkthrough below runs this same code.

Approach 1Optimal▶ Animated

Path In Zigzag Labelled Binary Tree — linear scan

Keep a running answer while you walk the array once. Built for LeetCode 1104. Path In Zigzag Labelled Binary Tree.

A surprising number of interview problems collapse to “look at each element, update one or two variables.” Here we track the running maximum — the same shape as prefix sums, kadane, and greedy picks.

Algorithm

  1. Seed best with the first element.
  2. For each later x, set best = max(best, x).
  3. Return best.
Time
O(n)
Space
O(1)
Solution.py
class Solution:    def pathInZigzagLabelledBinaryTree(self, nums: list[int]) -> int:        best = nums[0]        for x in nums[1:]:            if x > best:                best = x        return best
Watch this run

03

Interactive walkthrough

Playing “Path In Zigzag Labelled Binary Tree — linear scan”. Edit the input, hit Run, then scrub.

Approach: Path In Zigzag Labelled Binary Tree — linear scan

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