424

Author: TedTran2019

ruby/424-Longest-Repeating-Character-Replacement.rb

@@ -0,0 +1,30 @@
+def character_replacement(s, k)
+  return 0 if s.length.zero?
+  return 1 if s.length == 1
+
+  max = 0
+  window = []
+  dict = Hash.new(0)
+  left = 0
+  right = left
+  while true
+    break if s[right].nil?
+
+    char = s[right]
+    window << char
+    dict[char] += 1
+    until window.length - highest_freq(dict) <= k
+      dict[window.shift] -= 1
+      left += 1
+    end
+    max = window.length if window.length > max
+    right += 1
+  end
+  max
+end
+
+def highest_freq(dict)
+  max = 0
+  dict.each { |_k, v| max = v if v > max }
+  max
+end