Add currently solved exerises from Chapter 16

thinkcspy/Chapter-16-Exercises/kochsnowflake.py

@@ -0,0 +1,55 @@
+
+import turtle
+
+def createLSystem(numIters, axiom):
+    if numIters == 0:
+        return axiom
+    else:
+        return createLSystem(numIters - 1, processString(axiom))
+
+
+def processString(oldStr):
+    newstr = ""
+    for ch in oldStr:
+        newstr = newstr + applyRules(ch)
+
+    return newstr
+
+
+def applyRules(ch):
+    newstr = ""
+    if ch == 'F':
+        newstr = 'F-F++F-F'   # Rule 1
+    else:
+        newstr = ch    # no rules apply so keep the character
+
+    return newstr
+
+
+def drawLsystem(aTurtle, instructions, angle, distance):
+    for cmd in instructions:
+        if cmd == 'F':
+            aTurtle.forward(distance)
+        elif cmd == 'B':
+            aTurtle.backward(distance)
+        elif cmd == '+':
+            aTurtle.right(angle)
+        elif cmd == '-':
+            aTurtle.left(angle)
+
+
+def main():
+    inst = createLSystem(4, "F--F--F")
+    t = turtle.Turtle()
+    wn = turtle.Screen()
+
+    t.up()
+    t.back(200)
+    t.down()
+    t.speed(9)
+    drawLsystem(t, inst, 60, 5)
+
+    wn.exitonclick()
+
+
+main()