text: Lexicographically largest prime path from top | Python3 implementation of above approach ; Depth First Search ; Return if cell contain non prime number or obstacle , or going out of matrix or already visited the cell or already found the lexicographical largest path ; marking cell is already visited ; storing the lexicographical largest path index ; if reached the end of the matrix ; updating the final number of steps in lexicographical largest path ; moving diagonal ( trying lexicographical largest path ) ; moving cell right to current cell ; moving cell down to current cell . ; Print lexicographical largest prime path ; To count the number of step in lexicographical largest prime path ; To store the lexicographical largest prime path index ; To mark if the cell is already traversed or not ; traversing by DFS ; printing the lexicographical largest prime path ; Return the number of prime path in ther matrix . ; for each cell ; If on the top row or leftmost column , there is no path there . ; If non prime number ; Finding the matrix mapping by considering non prime number as obstacle and prime number be valid path . ; Sieve ; If prime ; if non prime ; Driver code
code: MAX = 105 NEW_LINE def sieve ( ) : NEW_LINE INDENT i = 2 NEW_LINE while ( i * i < MAX ) : NEW_LINE INDENT if ( prime [ i ] == 0 ) : NEW_LINE INDENT for j in range ( i * i , MAX , i ) : NEW_LINE INDENT prime [ j ] = 1 ; NEW_LINE DEDENT DEDENT i += 1 NEW_LINE DEDENT DEDENT def dfs ( i , j , k , q , n , m ) : NEW_LINE INDENT if ( mappedMatrix [ i ] [ j ] == 0 or i > n or j > m or mark [ i ] [ j ] or q != 0 ) : NEW_LINE INDENT return q ; NEW_LINE DEDENT mark [ i ] [ j ] = 1 ; NEW_LINE ans [ k ] = [ i , j ] NEW_LINE if ( i == n and j == m ) : NEW_LINE INDENT q = k ; NEW_LINE return q ; NEW_LINE DEDENT q = dfs ( i + 1 , j + 1 , k + 1 , q , n , m ) ; NEW_LINE q = dfs ( i + 1 , j , k + 1 , q , n , m ) ; NEW_LINE q = dfs ( i , j + 1 , k + 1 , q , n , m ) ; NEW_LINE return q NEW_LINE DEDENT def lexicographicalPath ( n , m ) : NEW_LINE INDENT q = 0 ; NEW_LINE global ans , mark NEW_LINE ans = [ [ 0 , 0 ] for i in range ( MAX ) ] NEW_LINE mark = [ [ 0 for j in range ( MAX ) ] for i in range ( MAX ) ] NEW_LINE q = dfs ( 1 , 1 , 1 , q , n , m ) ; NEW_LINE for i in range ( 1 , q + 1 ) : NEW_LINE INDENT print ( str ( ans [ i ] [ 0 ] ) + ' ▁ ' + str ( ans [ i ] [ 1 ] ) ) NEW_LINE DEDENT DEDENT def countPrimePath ( n , m ) : NEW_LINE INDENT global dp NEW_LINE dp = [ [ 0 for j in range ( MAX ) ] for i in range ( MAX ) ] NEW_LINE dp [ 1 ] [ 1 ] = 1 ; NEW_LINE for i in range ( 1 , n + 1 ) : NEW_LINE INDENT for j in range ( 1 , m + 1 ) : NEW_LINE INDENT if ( i == 1 and j == 1 ) : NEW_LINE INDENT continue ; NEW_LINE DEDENT dp [ i ] [ j ] = ( dp [ i - 1 ] [ j ] + dp [ i ] [ j - 1 ] + dp [ i - 1 ] [ j - 1 ] ) ; NEW_LINE if ( mappedMatrix [ i ] [ j ] == 0 ) : NEW_LINE INDENT dp [ i ] [ j ] = 0 ; NEW_LINE DEDENT DEDENT DEDENT print ( dp [ n ] [ m ] ) NEW_LINE DEDENT def preprocessMatrix ( a , n , m ) : NEW_LINE INDENT global prime NEW_LINE prime = [ 0 for i in range ( MAX ) ] NEW_LINE sieve ( ) ; NEW_LINE for i in range ( n ) : NEW_LINE INDENT for j in range ( m ) : NEW_LINE INDENT if ( prime [ a [ i ] [ j ] ] == 0 ) : NEW_LINE INDENT mappedMatrix [ i + 1 ] [ j + 1 ] = 1 ; NEW_LINE DEDENT else : NEW_LINE INDENT mappedMatrix [ i + 1 ] [ j + 1 ] = 0 ; NEW_LINE DEDENT DEDENT DEDENT DEDENT if __name__ == " _ _ main _ _ " : NEW_LINE INDENT n = 3 ; NEW_LINE m = 3 ; NEW_LINE a = [ [ 2 , 3 , 7 ] , [ 5 , 4 , 2 ] , [ 3 , 7 , 11 ] ] ; NEW_LINE mappedMatrix = [ [ 0 for j in range ( MAX ) ] for i in range ( MAX ) ] NEW_LINE preprocessMatrix ( a , n , m ) ; NEW_LINE countPrimePath ( n , m ) ; NEW_LINE lexicographicalPath ( n , m ) ; NEW_LINE DEDENT