go: add «664. Strange Printer»

Signed-off-by: Matej Focko <me@mfocko.xyz>

go/strange-printer.go

@@ -0,0 +1,57 @@
+package main
+
+import "strings"
+
+func strangePrinter(s string) int {
+	mergeConsecutive := func() string {
+		withoutConsecutive := strings.Builder{}
+
+		for i := 0; i < len(s); {
+			c := s[i]
+			withoutConsecutive.WriteByte(c)
+
+			for i < len(s) && s[i] == c {
+				i++
+			}
+		}
+
+		return withoutConsecutive.String()
+	}
+
+	compute := func(s string, dp [][]int, length int) {
+		for l := 0; l+length-1 < len(s); l++ {
+			r := l + length - 1
+
+			dp[l][r] = length
+
+			for mid := 0; mid < length-1; mid++ {
+				turns := dp[l][l+mid] + dp[l+mid+1][r]
+
+				if s[l+mid] == s[r] {
+					turns--
+				}
+
+				dp[l][r] = min(
+					dp[l][r],
+					turns,
+				)
+			}
+		}
+	}
+
+	s = mergeConsecutive()
+	n := len(s)
+
+	// Make a DP table
+	dp := make([][]int, n)
+	for i := range n {
+		dp[i] = make([]int, n)
+		dp[i][i] = 1
+	}
+
+	for length := 2; length <= n; length++ {
+		compute(s, dp, length)
+	}
+
+	return dp[0][n-1]
+}