Update 0202.快乐数.md 增加 Ruby 版本实现

problems/0202.快乐数.md

@@ -534,6 +534,30 @@ public class Solution {
 }
 ```
 
+### Ruby：
+
+```ruby
+# @param {Integer} n
+# @return {Boolean}
+def is_happy(n)
+    @occurred_nums = Set.new
+
+    while true
+        n = next_value(n)
+
+        return true if n == 1
+
+        return false if @occurred_nums.include?(n)
+            
+        @occurred_nums << n
+    end
+end
+
+def next_value(n)
+    n.to_s.chars.sum { |char| char.to_i ** 2 }
+end
+```
+
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