SRM496 - div2 - level two

srm496_div2_level2.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-

"""SRM496 - div2 - level two

Manao has a bitmap H pixels high and W pixels wide. 
Initially, each of the pixels is white. 
Manao draws several (possibly zero) horizontal and/or 
vertical strokes. A stroke is a line segment 1 pixel 
thick and 1 or more pixels long. Manao only draws horizontal 
strokes with red color and vertical strokes with blue. 
He can paint a one pixel long stroke with either red or 
blue color, and the stroke will be considered horizontal 
if red and vertical if blue. Manao never draws two 
horizontal or two vertical strokes that overlap. 
If a horizontal stroke and a vertical stroke cross, 
the pixel at their intersection becomes green.

You're given a String[] picture denoting the bitmap after 
Manao's drawing experiments. The x-th character of 
the y-th element of picture describes the color of 
the pixel at coordinates (x, y) of the bitmap, 
where (0, 0) is the pixel at the top left corner 
and (W-1, H-1) is the pixel at the bottom right corner. 
'R' is red, 'G' is green, 'B' is blue and '.' is white. 
Return the least possible number of strokes needed to 
obtain the given picture.

Definition:
    Class: ColoredStrokes
    Method: getLeast
    Parameters: String[]
    Returns: int
    Method signature: int getLeast(String[] picture)
"""

class ColoredStrokes(object):
    """Anagram Free

    Constraints:
        - picture will contain between 1 and 50 elements, 
          inclusive.
        - Each element of picture will be between 1 and 50 
          characters long, inclusive.
        - All elements of picture will have equal length.
        - Each character in picture will be 'R', 'G', 'B' or '.'.

    >>> strokes = ColoredStrokes()
    >>> print strokes.getLeast(["...", "...", ])
    0
    >>> print strokes.getLeast(["..B.", "..B.", ])
    1
    >>> print strokes.getLeast([".BB.", ])
    2
    >>> print strokes.getLeast(["...B..", ".BRGRR", ".B.B..", ])
    3
    >>> print strokes.getLeast(["...B..", ".BRBRR", ".B.B..", ])
    4
    >>> print strokes.getLeast(["GR", "BG", ])
    4
    """

    def __init__(self):
        pass

    def getLeast(self, picture):
        res = 0

        for y in range(len(picture)):
            for x in range(len(picture[0])):
                # Check red
                if picture[y][x] in ['R', 'G', ] and \
                        (x == 0 or picture[y][x - 1] in ['B', '.', ]):
                            res += 1
                # Check blue
                if picture[y][x] in ['B', 'G', ] and \
                        (y == 0 or picture[y - 1][x] in ['R', '.', ]):
                            res += 1
        return res

if __name__ == '__main__':
    import doctest
    doctest.testmod()