text: Unique paths covering every non | Javascript implementation of the approach ; Function for dfs . i , j == > Current cell indexes vis == > To mark visited cells ans == > Result z == > Current count 0 s visited z_count == > Total 0 s present ; Mark the block as visited ; update the count ; If end block reached ; If path covered all the non - obstacle blocks ; Up ; Down ; Left ; Right ; Unmark the block ( unvisited ) ; Function to return the count of the unique paths ; let z_count = 0 ; Total 0 s present ; Count non - obstacle blocks ; Starting position ; Driver code
code: let ans = 0 ; function dfs ( i , j , grid , vis , z , z_count ) { let n = grid . length , m = grid [ 0 ] . length ; vis [ i ] [ j ] = true ; if ( grid [ i ] [ j ] == 0 ) z ++ ; if ( grid [ i ] [ j ] == 2 ) { if ( z == z_count ) ans ++ ; vis [ i ] [ j ] = false ; return ; } if ( i >= 1 && ! vis [ i - 1 ] [ j ] && grid [ i - 1 ] [ j ] != - 1 ) dfs ( i - 1 , j , grid , vis , z , z_count ) ; if ( i < n - 1 && ! vis [ i + 1 ] [ j ] && grid [ i + 1 ] [ j ] != - 1 ) dfs ( i + 1 , j , grid , vis , z , z_count ) ; if ( j >= 1 && ! vis [ i ] [ j - 1 ] && grid [ i ] [ j - 1 ] != - 1 ) dfs ( i , j - 1 , grid , vis , z , z_count ) ; if ( j < m - 1 && ! vis [ i ] [ j + 1 ] && grid [ i ] [ j + 1 ] != - 1 ) dfs ( i , j + 1 , grid , vis , z , z_count ) ; vis [ i ] [ j ] = false ; } function uniquePaths ( grid ) { let n = grid . length , m = grid [ 0 ] . length ; let vis = new Array ( n ) ; for ( let i = 0 ; i < n ; i ++ ) { vis [ i ] = new Array ( m ) ; for ( let j = 0 ; j < m ; j ++ ) { vis [ i ] [ j ] = false ; } } let x = 0 , y = 0 ; for ( let i = 0 ; i < n ; ++ i ) { for ( let j = 0 ; j < m ; ++ j ) { if ( grid [ i ] [ j ] == 0 ) z_count ++ ; else if ( grid [ i ] [ j ] == 1 ) { x = i ; y = j ; } } } dfs ( x , y , grid , vis , 0 , z_count ) ; return ans ; } let grid = [ [ 1 , 0 , 0 , 0 ] , [ 0 , 0 , 0 , 0 ] , [ 0 , 0 , 2 , - 1 ] ] ; document . write ( uniquePaths ( grid ) ) ;