auto save

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
+goal = 20
+low = 0
+high = len(num_list)-1
+while low<=high:
+mid = (low+high)//2
+num = num_list[mid]
+if num==goal:
+    print('索引',mid)
+    break
+elif num<goal:
+    low = mid+1
+else:
+    high = mid-1
+'''
+def erfen(alist,number):
+    low = 0
+    high = len(alist)-1
+    while low<=high:
+        mid = (low+high)//2
+        num = num_list[mid]
+        if num == number:
+            #print('索引',mid)
+            #break
+        elif num<number:
+            low = mid+1
+        else:
+            high = mid-1
+    return None
+res =erfen(num_list,20)
+print(res)
\ No newline at end of file