How should I practice Universal Exit Command Sequence?

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

Is Universal Exit Command Sequence associated with Google?

FastPrep tags this as a Google onsite interview coding practice problem when the problem catalog has that company and stage context.

Universal Exit Command Sequence

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Problem statement

A rectangular maze uses # for walls, . for passable cells that may be the unknown start, and exactly one E exit. You must choose one fixed command string over U, D, L, and R.

Every possible start executes every command without feedback. A move into a wall or outside the grid leaves that possibility in place. A possibility that enters E terminates and is removed. Return the shortest command string that makes every possible start reach the exit. Break ties by exploring commands in U,D,L,R order.

Function

universalExitCommands(grid: String[]) → String

Examples

Example 1

grid = ["..E"]return = "RR"

Two right moves merge and then exit both possible starts.

Example 2

grid = ["..","E#"]return = "LD"

A horizontal merge followed by a downward move reaches the exit.

Constraints

1 <= rows, columns <= 20.
The grid is rectangular and contains exactly one E.
There are at most 20 dot cells.
A universal sequence is guaranteed to exist.