2020-05-09

Author: JiayangWu

0069.x的平方根/0069-x的平方根.py

@@ -4,18 +4,14 @@ def mySqrt(self, x):
         :type x: int
         :rtype: int
         """
-        if not x :
-            return 0
-        if x < 4:
-            return 1
-        start, end = 2, x // 2
-        while 1:
-            i = (start + end) // 2
-            if i ** 2 <= x and (i + 1) ** 2 >x:
-                return i
-            elif i ** 2 < x:
-                start = i + 1
-            elif i ** 2 > x:
-                end = i - 1
-                
-                
+        left, right = 1, x
+        while left <= right:
+            mid = (left + right) // 2
+            s = mid ** 2
+            if s == x:
+                return mid
+            elif s < x:
+                left = mid + 1
+            elif s > x:
+                right = mid - 1
+        return left - 1