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RatInAMaze prints path now

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Chiranjeev
2021-08-22 23:24:13 +05:30
parent 9b37cb0705
commit 51c5ea48b8
1 changed files with 43 additions and 30 deletions
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43
Backtracking/RatInAMaze.js
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@ -3,33 +3,48 @@
* - Given a NxN grid, find whether rat in cell (0,0) can reach target(N-1,N-1); * - 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 * - 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) => { const outOfBoundary = (grid, currentRow, currentColumn) => {
if (currentRow < 0 || currentColumn < 0 || currentRow >= grid.length || currentColumn >= grid[0].length) return true if (currentRow < 0 || currentColumn < 0 || currentRow >= grid.length || currentColumn >= grid[0].length) {
else return false return true
} else {
return false
}
} }
const isPossible = (grid, currentRow, currentColumn) => { const printPath = (grid, currentRow, currentColumn, path) => {
// If cell is out of boundary, we can't proceed
if (outOfBoundary(grid, currentRow, currentColumn)) return false 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 (grid[currentRow][currentColumn] === 0) return false
// If we reached target cell, then print path
if (currentRow === targetRow && currentColumn === targetColumn) { if (currentRow === targetRow && currentColumn === targetColumn) {
console.log(path)
return true return true
} }
// R,L,D,U are directions `Right, Left, Down, Up`
const directions = [ const directions = [
[1, 0], [1, 0, 'D'],
[0, 1], [-1, 0, 'U'],
[-1, 0], [0, 1, 'R'],
[0, -1] [0, -1, 'L']
] ]
for (let i = 0; i < directions.length; i++) { for (let i = 0; i < directions.length; i++) {
const nextRow = currentRow + directions[i][0]; const nextColumn = currentColumn + directions[i][1] const nextRow = currentRow + directions[i][0]
const nextColumn = currentColumn + directions[i][1]
const updatedPath = path + directions[i][2]
grid[currentRow][currentColumn] = 0 grid[currentRow][currentColumn] = 0
if (isPossible(grid, nextRow, nextColumn)) return true if (printPath(grid, nextRow, nextColumn, updatedPath)) return true
grid[currentRow][currentColumn] = 1 grid[currentRow][currentColumn] = 1
} }
return false return false
@ -40,15 +55,13 @@ const isPossible = (grid, currentRow, currentColumn) => {
const grid = [ const grid = [
[1, 1, 1, 1], [1, 1, 1, 1],
[1, 0, 0, 1], [1, 0, 0, 1],
[0, 0, 1, 0], [0, 0, 1, 1],
[1, 1, 0, 1] [1, 1, 0, 1]
] ]
const targetRow = grid.length - 1 const targetRow = grid.length - 1
const targetColumn = grid[0].length - 1 const targetColumn = grid[0].length - 1
if (isPossible(grid, 0, 0)) { // Variation 2 : print a possible path to reach from (0, 0) to (N-1, N-1)
console.log('Possible') // If there is no path possible then it will print "Not Possible"
} else { !printPath(grid, 0, 0, '') && console.log('Not Possible')
console.log('Not Possible')
}