1. Empty is zero
A missing subtree contributes no depth.
if (root === null) {
return 0;
}Typorithm · easy
Maximum Depth
max-depth-binary-treetreesrecursiondfsheight
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Full lesson · 8 learning steps Open any exercise for focused practice
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Step 1 of 8 · intro card
Learn Maximum Depth
Trees
Depth equals one plus the maximum depth of the two subtrees, with empty subtrees counting as zero.
The depth of a tree is the longest path from the root down to a leaf.
Each node adds one to the deeper of its two subtrees.
The base case — an empty subtree — has depth zero, anchoring the recursion.
01
Empty subtree depth is 0.
02
Take the max of both children.
03
Add 1 for the current node.
function maxDepth(root) {
if (root === null) {
return 0;
}
return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
}Read the implementation
Connect each part of the code to the concept before you type.
2. Deeper child
Depth is driven by the taller subtree.
Math.max(maxDepth(root.left), maxDepth(root.right))3. Count this node
Add one for the current node above its children.
1 + Math.maxA complete learning loop
01
Understand
Read the concept map and follow the code breakdown.
02
Reconstruct
Type the implementation, repair mistakes and work through every recall exercise.
03
Verify
Use the final check without hints; revisit weak concepts in short practice sessions.