Search⌘ K
AI Features
Home
Courses
Grokking the Coding Interview Patterns in Python

Solution: Unique Paths III

Explore how to apply backtracking to solve the Unique Paths III problem, finding all paths that visit every empty square exactly once between fixed start and end points. Understand the recursive exploration, marking visited cells, and efficient backtracking to count valid paths within grid constraints.

We'll cover the following...

Statement

You are given a  m×nm \times n  integer array, grid, where each cell, grid[i][j], can have one of the following values:

  • 1 indicates the starting point. There is exactly one such square.

  • 2 marks the ending point. There is exactly one such square.

  • 0 represents empty squares that can be walked over.

  • -1 represents obstacles that cannot be crossed.

Your task is to return the total number of unique four-directional paths from the starting square (1) to the ending square (2), such that every empty square is visited ...