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binary_search.py

 # 使用二分查找法，找出9和20在列表里面的索引
 # 使用二分查找法，找出9和20在列表里面的索引
-num_list = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
+num_list = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
\ No newline at end of file
+low=0
+high=len(num(list)-1)
+mid=(low+high)//2
+while True:    
+    if 20 in num_list[:mid]:
+        num_list.
+        high=mid
+    else:
+        num_list.pop(mid:)
+        low=mid
+    if high==low and low==mid:
+        print("找到了")
+        print(low)
+        break
+    
+    
+

demo.py

+import turtle
+import random
+
+pen=turtle.Pen()
+pen.color("sandybrown")
+
+sc=turtle.Screen()
+sc.bgcolor("wheat")
+pen.left(90)
+pen.up()
+pen.backward(300)
+pen.down()
+def tree(n):
+    if n>0:
+        if n<=12:
+            color_list=["snow","pink"]
+            colors=random.choice(color_list)
+            pen.pencolor(colors)
+            pen.pensize(n/3)
+        else:
+            pen.pensize(n/10)
+            pen.pencolor("sandybrown")
+        angle=random.randint(0,30)
+        length=random.randint(1,15)
+        pen.forward(n)
+        pen.right(angle)
+        tree(n-length)
+        pen.left(angle*2)
+        tree(n-length)
+        pen.right(angle)
+        pen.up()
+        pen.backward(n)
+        pen.down()
+
+tree(100)
+turtle.done()
\ No newline at end of file