Merge pull request keon#153 from christianbender/changed_bomb_enemy

Changed bomb_enemy.py in directory matrix

matrix/bomb_enemy.py

@@ -1,42 +1,48 @@
-# Given a 2D grid, each cell is either a wall 'W',
-# an enemy 'E' or empty '0' (the number zero),
-# return the maximum enemies you can kill using one bomb.
-# The bomb kills all the enemies in the same row and column from
-# the planted point until it hits the wall since the wall is too strong
-# to be destroyed.
-# Note that you can only put the bomb at an empty cell.
+"""
+Given a 2D grid, each cell is either a wall 'W',
+an enemy 'E' or empty '0' (the number zero),
+return the maximum enemies you can kill using one bomb.
+The bomb kills all the enemies in the same row and column from
+the planted point until it hits the wall since the wall is too strong
+to be destroyed.
+Note that you can only put the bomb at an empty cell.
 
-# Example:
-# For the given grid
+Example:
+For the given grid
 
-# 0 E 0 0
-# E 0 W E
-# 0 E 0 0
+0 E 0 0
+E 0 W E
+0 E 0 0
 
-# return 3. (Placing a bomb at (1,1) kills 3 enemies)
+return 3. (Placing a bomb at (1,1) kills 3 enemies)
+"""
 
 def max_killed_enemies(grid):
     if not grid: return 0
     m, n = len(grid), len(grid[0])
     max_killed = 0
     row_e, col_e = 0, [0] * n
+    # iterates over all cells in the grid
     for i in range(m):
         for j in range(n):
+            # makes sure we are next to a wall.
             if j == 0 or grid[i][j-1] == 'W':
                 row_e = row_kills(grid, i, j)
-
+            # makes sure we are next to a wall.
             if i == 0 or grid[i-1][j] == 'W':
                 col_e[j] = col_kills(grid, i, j)
-
+            # makes sure the cell contains a 0
             if grid[i][j] == '0':
+                # updates the variable
                 max_killed = max(max_killed, row_e + col_e[j])
 
     return max_killed
 
 # calculate killed enemies for row i from column j
 def row_kills(grid, i, j):
     num = 0
-    while j < len(grid[0]) and grid[i][j] != 'W':
+    len_row = len(grid[0])
+    while j < len_row and grid[i][j] != 'W':
         if grid[i][j] == 'E':
             num += 1
         j += 1
@@ -45,18 +51,43 @@ def row_kills(grid, i, j):
 # calculate killed enemies for  column j from row i
 def col_kills(grid, i, j):
     num = 0
-    while i < len(grid) and grid[i][j] != 'W':
+    len_col = len(grid)
+    while i < len_col and grid[i][j] != 'W':
         if grid[i][j] == 'E':
             num += 1
         i += 1
     return num
+
+
+
+# ----------------- TESTS -------------------------
+
+"""
+    Testsuite for the project
+"""
+
+import unittest 
 
-grid = [
-["0", "E", "0", "E"],
-["E", "E", "E", "0"],
-["E", "0", "W", "E"],
-["0", "E", "0", "0"]]
-print(grid)
+class TestBombEnemy(unittest.TestCase):
+    def test_3x4(self):
+        grid1 = [["0","E","0","0"],
+                ["E","0","W","E"],
+                ["0","E","0","0"]]
+        self.assertEqual(3,max_killed_enemies(grid1))
+    def test_4x4(self):
+        grid1 = [
+                ["0", "E", "0", "E"],
+                ["E", "E", "E", "0"],
+                ["E", "0", "W", "E"],
+                ["0", "E", "0", "0"]]
+        grid2 = [
+                ["0", "0", "0", "E"],
+                ["E", "0", "0", "0"],
+                ["E", "0", "W", "E"],
+                ["0", "E", "0", "0"]]
+        self.assertEqual(5,max_killed_enemies(grid1))
+        self.assertEqual(3,max_killed_enemies(grid2))
 
-print(max_killed_enemies(grid))
+if __name__ == "__main__":
+    unittest.main()