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]
+a1 = 9
+low = 0
+high = len(num_list) - 1
+
+while low <=high:
+    mid = (low+high) //2
+    if a1 == num_list[mid]:
+        print("找到了",a1,"的位置",mid)
+        break
+    elif mid < a1:
+        low = mid + 1
+    else:
+        high = mid - 1
+if high < low:
+    print("没有",a1,"这个数")
+
+a1 = 20
+low = 0
+high = len(num_list) - 1
+
+while low <=high:
+    mid = (low+high) //2
+    if a1 == num_list[mid]:
+        print("找到了",a1,"的位置",mid)
+        break
+    elif mid < a1:
+        low = mid + 1
+    else:
+        high = mid - 1
+if high < low:
+    print("没有",a1,"这个数")
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