Create valid_perfect_square.py

yingl · web-flow · commit ea69035e9254 · 2019-02-19T21:54:42.000+08:00
diff --git a/valid_perfect_square.py b/valid_perfect_square.py
@@ -0,0 +1,20 @@
+class Solution:
+    """
+    @param num: a positive integer
+    @return: if num is a perfect square else False
+    """
+    def isPerfectSquare(self, num):
+        # write your code here
+        i, j = 0, num
+        while i <= j:
+            k = int((i + j) / 2) # 二分收敛
+            k2 = k * k
+            if k2 == num:
+                return True
+            elif k2 > num:
+                j = k - 1
+            else:
+                i = k + 1
+        return False
+
+# easy: https://www.lintcode.com/problem/valid-perfect-square
