diff --git a/Backtracking/RatInAMaze.js b/Backtracking/RatInAMaze.js new file mode 100644 index 000000000..df38c4545 --- /dev/null +++ b/Backtracking/RatInAMaze.js @@ -0,0 +1,67 @@ +/* + * Problem Statement: + * - Given a NxN grid, find whether rat in cell (0,0) can reach target(N-1,N-1); + * - In grid "0" represent blocked cell and "1" represent empty cell + * + * Reference for this problem: + * - https://www.geeksforgeeks.org/rat-in-a-maze-backtracking-2/ + * + */ + +// Helper function to find if current cell is out of boundary +const outOfBoundary = (grid, currentRow, currentColumn) => { + if (currentRow < 0 || currentColumn < 0 || currentRow >= grid.length || currentColumn >= grid[0].length) { + return true + } else { + return false + } +} + +const printPath = (grid, currentRow, currentColumn, path) => { + // If cell is out of boundary, we can't proceed + if (outOfBoundary(grid, currentRow, currentColumn)) return false + + // If cell is blocked then you can't go ahead + if (grid[currentRow][currentColumn] === 0) return false + + // If we reached target cell, then print path + if (currentRow === targetRow && currentColumn === targetColumn) { + console.log(path) + return true + } + + // R,L,D,U are directions `Right, Left, Down, Up` + const directions = [ + [1, 0, 'D'], + [-1, 0, 'U'], + [0, 1, 'R'], + [0, -1, 'L'] + ] + + for (let i = 0; i < directions.length; i++) { + const nextRow = currentRow + directions[i][0] + const nextColumn = currentColumn + directions[i][1] + const updatedPath = path + directions[i][2] + + grid[currentRow][currentColumn] = 0 + if (printPath(grid, nextRow, nextColumn, updatedPath)) return true + grid[currentRow][currentColumn] = 1 + } + return false +} + +// Driver Code + +const grid = [ + [1, 1, 1, 1], + [1, 0, 0, 1], + [0, 0, 1, 1], + [1, 1, 0, 1] +] + +const targetRow = grid.length - 1 +const targetColumn = grid[0].length - 1 + +// Variation 2 : print a possible path to reach from (0, 0) to (N-1, N-1) +// If there is no path possible then it will print "Not Possible" +!printPath(grid, 0, 0, '') && console.log('Not Possible')