Count number of ways to reach destination in a Maze | JavaScript program to count number of paths in a maze with obstacles . ; Returns count of possible paths in a maze [ R ] [ C ] from ( 0 , 0 ) to ( R - 1 , C - 1 ) ; If the initial cell is blocked , there is no way of moving anywhere ; Initializing the leftmost column ; If we encounter a blocked cell in leftmost row , there is no way of visiting any cell directly below it . ; Similarly initialize the topmost row ; If we encounter a blocked cell in bottommost row , there is no way of visiting any cell directly below it . ; The only difference is that if a cell is - 1 , simply ignore it else recursively compute count value maze [ i ] [ j ] ; If blockage is found , ignore this cell ; If we can reach maze [ i ] [ j ] from maze [ i - 1 ] [ j ] then increment count . ; If we can reach maze [ i ] [ j ] from maze [ i ] [ j - 1 ] then increment count . ; If the final cell is blocked , output 0 , otherwise the answer ; Driver Code
let R = 4 ; let C = 4 ; function countPaths ( maze ) { if ( maze [ 0 ] [ 0 ] == - 1 ) return 0 ; for ( let i = 0 ; i < R ; i ++ ) { if ( maze [ i ] [ 0 ] == 0 ) maze [ i ] [ 0 ] = 1 ; else break ; } for ( let i = 1 ; i < C ; i ++ ) { if ( maze [ 0 ] [ i ] == 0 ) maze [ 0 ] [ i ] = 1 ; else break ; } for ( let i = 1 ; i < R ; i ++ ) { for ( let j = 1 ; j < C ; j ++ ) { if ( maze [ i ] [ j ] == - 1 ) continue ; if ( maze [ i - 1 ] [ j ] > 0 ) maze [ i ] [ j ] = ( maze [ i ] [ j ] + maze [ i - 1 ] [ j ] ) ; if ( maze [ i ] [ j - 1 ] > 0 ) maze [ i ] [ j ] = ( maze [ i ] [ j ] + maze [ i ] [ j - 1 ] ) ; } } return ( maze [ R - 1 ] [ C - 1 ] > 0 ) ? maze [ R - 1 ] [ C - 1 ] : 0 ; } let maze = [ [ 0 , 0 , 0 , 0 ] , [ 0 , - 1 , 0 , 0 ] , [ - 1 , 0 , 0 , 0 ] , [ 0 , 0 , 0 , 0 ] ] ; document . write ( countPaths ( maze ) ) ;