How should I practice Lexicographically Smallest Root-to-Leaf String?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Bloomberg LP onsite interview problems in FastPrep.

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Lexicographically Smallest Root-to-Leaf String

Bloomberg LP● MediumNEW GRADONSITE INTERVIEW

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Problem statement

Each binary-tree node contains an integer from 0 through 25 representing letters a through z. Return the lexicographically smallest string encountered along a path from the root to any leaf.

Return the empty string for an empty tree.

Function

smallestRootToLeaf(root: TreeNode) → String

Examples

Example 1

root = [0,1,2,3,4,3,4]return = "abd"

The root-to-leaf strings are abd, abe, acd, and ace; abd is smallest.

Constraints

The tree contains at most 10^5 nodes.
Every node value is between 0 and 25.