155

Author: TedTran2019

ruby/155-Min-Stack.rb

@@ -0,0 +1,33 @@
+class MinStack
+  def initialize
+    @stack = []
+  end
+
+  def push(val)
+    min = if @stack.empty?
+            val
+          else
+            val < @stack.last[1] ? val : @stack.last[1]
+          end
+
+    @stack << [val, min]
+    nil
+  end
+
+  def pop
+    @stack.pop
+    nil
+  end
+
+  def top
+    return nil if @stack.empty?
+
+    @stack.last[0]
+  end
+
+  def get_min
+    return nil if @stack.empty?
+
+    @stack.last[1]
+  end
+end