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=9
-wc=20
-while low <= high:
-    mid=(low+high)//2 
-    wmid = num_list[mid]
-    if wmid == wc:
-        print("  vvc",wmid)
-        break
-    elif wmid<wc:
-        low = mid+1
-    elif wmid>wc:
-        high=mid-1
+import random
+
+alist = []
+for i in range(1,101):
+    alist.append(i)
+num = random.choice(alist)
+def binary_search(alist,num):
+    low=0
+    high= len(alist)-1
+    while low <= high:
+        mid=(low+high)//2 
+        wmid = alist[mid]
+        if wmid == num:
+            return(mid)
+        elif wmid<num:
+            low = mid+1
+        elif wmid>num:
+            high=mid-1
+    return None  
+wc = binary_search(alist,num)
+print('老师给的数是',num)
+print('他在列表里的索引是',wc)
+
+