Update 0202.快乐数.md

problems/0202.快乐数.md

@@ -108,23 +108,14 @@ class Solution {
 ```
 
 Python：
+(版本一)使用集合
 ```python
 class Solution:
     def isHappy(self, n: int) -> bool:        
-        def calculate_happy(num):
-            sum_ = 0
-            
-            # 从个位开始依次取，平方求和
-            while num:
-                sum_ += (num % 10) ** 2
-                num = num // 10
-            return sum_
-
-        # 记录中间结果
         record = set()
 
         while True:
-            n = calculate_happy(n)
+            n = self.get_sum(n)
             if n == 1:
                 return True
             
@@ -134,21 +125,86 @@ class Solution:
             else:
                 record.add(n)
 
-# python的另一种写法 - 通过字符串来计算各位平方和
+    def get_sum(self,n: int) -> int: 
+        new_num = 0
+        while n:
+            n, r = divmod(n, 10)
+            new_num += r ** 2
+        return new_num
+ ```  
+ (版本二)使用集合
+ ```python
+class Solution:
+    def isHappy(self, n: int) -> bool:
+        record = set()
+        while n not in record:
+            record.add(n)
+            new_num = 0
+            n_str = str(n)
+            for i in n_str:
+                new_num+=int(i)**2
+            if new_num==1: return True
+            else: n = new_num
+        return False
+```
+ (版本三)使用数组
+ ```python
 class Solution:
     def isHappy(self, n: int) -> bool:
         record = []
         while n not in record:
             record.append(n)
-            newn = 0
+            new_num = 0
-            nn = str(n)
+            n_str = str(n)
-            for i in nn:
+            for i in n_str:
-                newn+=int(i)**2
+                new_num+=int(i)**2
-            if newn==1: return True
+            if new_num==1: return True
-            n = newn
+            else: n = new_num
         return False
 ```
-
+ (版本四)使用快慢指针
+ ```python
+class Solution:
+    def isHappy(self, n: int) -> bool:        
+        slow = n
+        fast = n
+        while self.get_sum(fast) != 1 and self.get_sum(self.get_sum(fast)):
+            slow = self.get_sum(slow)
+            fast = self.get_sum(self.get_sum(fast))
+            if slow == fast:
+                return False
+        return True
+    def get_sum(self,n: int) -> int: 
+        new_num = 0
+        while n:
+            n, r = divmod(n, 10)
+            new_num += r ** 2
+        return new_num
+```
+ (版本五)使用集合+精简
+ ```python
+class Solution:
+    def isHappy(self, n: int) -> bool:
+        seen = set()
+        while n != 1:
+            n = sum(int(i) ** 2 for i in str(n))
+            if n in seen:
+                return False
+            seen.add(n)
+        return True
+```
+ (版本六)使用数组+精简
+ ```python
+class Solution:
+    def isHappy(self, n: int) -> bool:
+        seen = []
+        while n != 1:
+            n = sum(int(i) ** 2 for i in str(n))
+            if n in seen:
+                return False
+            seen.append(n)
+        return True
+```
 Go：
 ```go
 func isHappy(n int) bool {