Given a matrix, you need to create another matrix such that the value (i,j) is either -1, 0 or 1.

__author__ = 'nitin'

"""Given a matrix, you need to create another matrix such that the value (i,j) is either -1, 0 or 1.
1 - if multiplication of all values in ith row and jth column is greater than 0.
-1 - if multiplication of all values in ith row and jth column is less than 0.
0 - if multiplication of all the values in ith row and jth column is 0.

e.g.
1 2 3 1
1 0 -1 2
-1 1 1 1

o/p
-1 0 -1 1
0 0 0 0
1 0 1 -1 """


matrix=[[1, 2, 3, 1], [1, 0, -1, 2], [-1, 1, 1, 1]]

def column_multiplication(rows,col_elem):
    col_result=1
    while rows>0:
        col_result=col_result * matrix[rows-1][col_elem]
        rows=rows-1
    return col_result

def rows_multiplication(col,row_elem):
    rows_result=1
    while col>0:
        rows_result=rows_result * matrix[row_elem][col-1]
        col=col-1
    return rows_result

def main():
    print "\nGiven Matrix : ", matrix, "\n"
    rows=len(matrix)
    col=len(matrix[0])
    new_matrix=[ [ None for i in range(col) ] for j in range(rows) ]
    for row_elem in range(rows):
        for col_elem in range(col):
            col_result=column_multiplication(rows,col_elem)
            rows_result=rows_multiplication(col,row_elem)
            if col_result * rows_result == 0:
                new_matrix[row_elem][col_elem]= 0
            elif col_result * rows_result > 0:
                new_matrix[row_elem][col_elem]= 1
            elif col_result * rows_result < 0:
                new_matrix[row_elem][col_elem]= -1
    print "Result Matrix : ", new_matrix

if __name__=="__main__":
    main()

5 Winning steps to crack coding interview

Ask questions. You want to make sure you understand what you’re being asked to solve.

Talk out loud as you solve the problem. The interviewer wants to know how you think and problem solve. If you remain quiet, it’s harder to ascertain that.

Openly discuss the trade offs in your algorithm decisions. Acknowledging the weak links in your approach demonstrates that you’re aware where potential trouble spots may arise, and offers up why you were willing to make your trade-offs.

Write code. Although you can sketch out pseudo code for an outline, you need to inform interviewers that’s what you’re doing so they don’t assume it’s your final version. After writing pseudo code, you’ll need to hunker down and write the actual code.

Test your code. Interviewers expect to see bugs, so don’t be shy about fixing them. What they’re looking for is how you fix the bugs. If each interviewer notices a pattern where you take a band-aid approach that’s likely to introduce other problems, don’t expect to be hired.