1、关于可视化递归问题
import turtle def tree(branchLen, t): if branchLen > 5: t.forward(branchLen) t.right(20) tree(branchLen-15, t) t.left(40) tree(branchLen-15, t) t.right(20) t.backward(branchLen) def main(): t = turtle.Turtle() myWin = turtle.Screen() t.left(90) t.up() t.backward(100) t.down() t.color("green") tree(75, t) myWin.exitonclick() main() |
2、The Binary Search（二分法搜索）
# 正常实现def BinarySearch(alist, item): first = 0 last = len(alist)-1 found = False while first <= last and not found: mindpoint = (last+first)//2 if alist[mindpoint] == item: found = True else: if item < alist[mindpoint]: last = mindpoint - 1 else: first = mindpoint + 1 return found # 引用递归实现def RBinarySearch(alist, item): if len(alist) == 0: return False else: mindpoint = len(alist)//2 if alist[mindpoint] == item: return True else: if item < alist[mindpoint]: return RBinarySearch(alist[:mindpoint], item) else: return RBinarySearch(alist[mindpoint+1:], item) testlist = [0, 1, 2, 8, 13, 17, 19, 32, 42]print(BinarySearch(testlist, 3))print(RBinarySearch(testlist, 13)) |