Merge pull request #287 from xiao2shiqi/phoenix-work-branch

添加 0020 有效的括号，0027 移除元素 Ruby 版本

problems/0015.三数之和.md

@@ -336,6 +336,23 @@ var threeSum = function(nums) {
 ```
 
 
+ruby:
+```ruby
+def is_valid(strs)
+    symbol_map = {')' => '(', '}' => '{', ']' => '['}
+    stack = []
+    strs.size.times {|i|
+        c = strs[i]
+        if symbol_map.has_key?(c)
+            top_e = stack.shift
+            return false if symbol_map[c] != top_e
+        else
+            stack.unshift(c)
+        end
+    }
+    stack.empty?
+end
+```
 
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 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)

problems/0027.移除元素.md

@@ -186,6 +186,20 @@ var removeElement = (nums, val) => {
 };
 ```
 
+Ruby:
+```ruby
+def remove_element(nums, val)
+    i = 0
+    nums.each_index do |j| 
+        if nums[j] != val
+            nums[i] = nums[j]
+            i+=1
+        end
+    end
+    i
+end
+```
+
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 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)