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
-num_list = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
-low = 0
-high = len(num_list)-1
-num = 21
+list = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
 
-while low<=high:
-    mid = (low+high)//2
-    guess = num_list[mid]
-    if guess == num:
-        print("找到了,索引是",mid)
-        break
-    elif guess<num:
-        low+=1
-    elif guess>num:
-        high-=1
\ No newline at end of file
+def find(num_list,num):
+    low = 0
+    high = len(num_list)-1
+    while low<=high:
+        mid = (low+high)//2
+        guess = num_list[mid]
+        if guess == num:
+            return mid
+        elif guess<num:
+            low=mid+1
+        else:
+            high = mid-1
+    return None
+a = find(list,20)
+print(a)
\ No newline at end of file