Merge pull request sashaaero#14 from aki1221/leet_961

leet code 961 ruby

Author: sashaaero

leet_961.rb

@@ -0,0 +1,13 @@
+# https://leetcode.com/problems/N-Repeated Element in Size 2N Array/
+# Runtime: 48 ms, faster than 81.88% of ruby online submissions for N-Repeated Element in Size 2N Array
+def repeated_n_times(a)
+  ans = Hash.new(0)
+  a.each do |k|
+    if ans[k] > 1
+      return k
+    else
+      ans[k] +=1
+    end
+  end
+  return ans.max_by{|k,v| v}[0]
+end