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RatInAMaze added in Backtracking #664

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Merged
raklaptudirm merged 3 commits into from
Aug 23, 2021
Merged

RatInAMaze added in Backtracking #664

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832aa6e
RatInAMaze added in Backtracking
chiranjeev-thapliyal Aug 22, 2021
9b37cb0
removed console lines from RatInAMaze
chiranjeev-thapliyal Aug 22, 2021
51c5ea4
RatInAMaze prints path now
chiranjeev-thapliyal Aug 22, 2021
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67 changes: 67 additions & 0 deletions Backtracking/RatInAMaze.js
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Original file line number Diff line number Diff line change
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/*
* 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')