0664

Author: theforestvn88

0601-0700/0664_strange_printer.rb

@@ -0,0 +1,24 @@
+# @param {String} s
+# @return {Integer}
+def strange_printer(s)
+    dp = Array.new(s.length) { Array.new(s.length, Float::INFINITY) }
+
+    (s.length-1).downto(0) { |i|
+        dp[i][i] = 1
+        (i+1...s.length).each { |j|
+            # assume s[i..j] like a...a
+            # we always need to print the first character 'a',
+            # the optimize way is we print all 'a' from i to j,
+            # hence the last character is also printed if they are the same
+            if s[j] == s[i]
+                dp[i][j] = dp[i][j-1]
+            else
+                (i+1..j).each { |k|
+                    dp[i][j] = [dp[i][j], dp[i][k-1] + dp[k][j]].min
+                }
+            end
+        }
+    }
+
+    dp[0][s.length-1]
+end