Update 0704.二分查找.md

Author: janeyziqinglin

problems/0704.二分查找.md

@@ -218,19 +218,21 @@ class Solution:
 
 （版本二）左闭右开区间
 
-```python
-class Solution:
+```class Solution:
     def search(self, nums: List[int], target: int) -> int:
-        left,right  =0, len(nums)
-        while left < right:
-            mid = (left + right) // 2
-            if nums[mid] < target:
-                left = mid+1
-            elif nums[mid] > target:
-                right = mid
+        if nums is None or len(nums)==0:
+            return -1
+        l=0
+        r=len(nums)-1
+        while (l<=r):
+            m = round(l+(r-l)/2)
+            if nums[m] == target:
+                return m     
+            elif nums[m] > target:
+                r=m-1
             else:
-                return mid
-        return -1
+                l=m+1
+        return -1 
 ```
 
 **Go：**