[v3] Move existing exercises to exercises/practice

exercises/practice/rectangles/example.py

@@ -0,0 +1,109 @@
+import itertools
+
+
+class Corners:
+    def __init__(self, i, j):
+        # i, j are position of corner
+        self.i = i
+        self.j = j
+
+    def __str__(self):
+        return "[" + str(self.i) + ", " + str(self.j) + "]"
+
+
+# return corner on the same line
+def same_line(index, list):
+    for corner in list:
+        if corner.i == index:
+            return corner
+
+
+# return corner on the same column
+def same_col(index, list):
+    for corner in list:
+        if corner.j == index:
+            return corner
+
+
+def search_corners(input):
+
+    return [Corners(item, element) for item in range(len(input))
+            for element in range(len(input[item]))
+            if (input[item][element] == "+")]
+
+
+# validate that 4 points form a rectangle by
+# comparing distance to centroid of the rectangle for all corners
+def possible_rect(quartet):
+    mid_x = 0
+    mid_y = 0
+
+    for centroid in quartet:
+        mid_x = mid_x + centroid.i / 4.0
+        mid_y = mid_y + centroid.j / 4.0
+
+    # reference distance using first corner
+    dx = abs(quartet[0].i - mid_x)
+    dy = abs(quartet[0].j - mid_y)
+
+    # Check all the same distance from centroid are equals
+    for i in range(1, len(quartet)):
+        if abs(quartet[i].i - mid_x) != dx or abs(quartet[i].j - mid_y) != dy:
+            return False
+    return True
+
+
+# validate path between two corners
+def path(corner1, corner2, input):
+    if corner1.i == corner2.i:
+        for j in range(min(corner1.j + 1, corner2.j + 1),
+                       max(corner1.j, corner2.j)):
+            if input[corner1.i][j] != "-" and input[corner1.i][j] != "+":
+                return False
+        return True
+
+    elif corner1.j == corner2.j:
+        for i in range(min(corner1.i + 1, corner2.i + 1),
+                       max(corner1.i, corner2.i)):
+            if input[i][corner1.j] != "|" and input[i][corner1.j] != "+":
+                return False
+        return True
+
+
+# validate path of rectangle
+def validate_rect(rectangle, input):
+    # validate connection at every corner
+    # with neighbours on the same line and col
+    for i in range(0, len(rectangle)):
+        line = same_line(rectangle[i].i, rectangle[0:i] + rectangle[i + 1:])
+        column = same_col(rectangle[i].j, rectangle[0:i] + rectangle[i + 1:])
+
+        if ((not path(rectangle[i], line, input)) or
+                (not path(rectangle[i], column, input))):
+            return False
+
+    return True
+
+
+# count number of rectangles inside ASCII in input lines
+def rectangles(strings=""):
+    rectangle_total = 0
+    # test empty str
+    if not strings:
+        return rectangle_total
+
+    corners = search_corners(strings)
+
+    # no corners in str
+    if not len(corners):
+        return rectangle_total
+
+    # all combinations of 4 corners
+    quartets = list(itertools.combinations(corners, r=4))
+    paths = (quartet for quartet in quartets if possible_rect(quartet))
+
+    # validate paths
+    for path in paths:
+        if validate_rect(path, strings):
+            rectangle_total += 1
+    return rectangle_total