save project

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
 a = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
 a = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
-b=0
-c=len(a)-1
-
-while b<=c:
-    d=(b+c)//2
-    if d==9:
-        print("索引是：",d)
+def f(a,num):
+    low=0
+    high=len(a)-1
+    while low<=high:
+        mid=(low+high)//2
+        guess=a[mid]
+        if guess==num:
+            return mid
             break
             break
-    elif d<9:
-        b=d+1
+        elif guess<num:
+            low=mid+1
         else:
         else:
-        c=d-1
-    
+            high=mid-1
+result=f(a,20)
\ No newline at end of file
+print("老师给的数："20)
+print("索引是：",result)
\ No newline at end of file