Merge pull request #522 from vaskoz/day253

Day253

README.md

@@ -263,3 +263,4 @@ problems from
 * [Day 249](https://github.com/vaskoz/dailycodingproblem-go/issues/514)
 * [Day 251](https://github.com/vaskoz/dailycodingproblem-go/issues/517)
 * [Day 252](https://github.com/vaskoz/dailycodingproblem-go/issues/519)
+* [Day 253](https://github.com/vaskoz/dailycodingproblem-go/issues/521)

day253/problem.go

@@ -0,0 +1,47 @@
+package day253
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+var (
+	// nolint
+	out io.Writer = os.Stdout
+)
+
+// PrintZigZag prints k lines of a zig-zag pattern for
+// the letters given.
+func PrintZigZag(letters string, k int) {
+	lines := make([]strings.Builder, k)
+	pos := 0
+	goingUp := false
+	for _, r := range letters {
+		switch {
+		case pos == k:
+			goingUp = true
+			pos -= 2
+		case pos == -1:
+			goingUp = false
+			pos += 2
+		}
+		for i := range lines {
+			if i == pos {
+				lines[i].WriteRune(r)
+			} else {
+				lines[i].WriteRune(' ')
+			}
+		}
+		switch {
+		case goingUp:
+			pos--
+		case !goingUp:
+			pos++
+		}
+	}
+	for _, line := range lines {
+		fmt.Fprintln(out, line.String())
+	}
+}

day253/problem_test.go

@@ -0,0 +1,38 @@
+package day253
+
+import (
+	"bytes"
+	"testing"
+)
+
+// nolint
+var testcases = []struct {
+	letters  string
+	k        int
+	expected string
+}{
+	{"thisisazigzag", 4, "t     a     g\n h   s z   a \n  i i   i z  \n   s     g   \n"},
+}
+
+func TestPrintZigZag(t *testing.T) {
+	// don't run in parallel due to global var
+	for _, tc := range testcases {
+		buff := new(bytes.Buffer)
+		out = buff
+		PrintZigZag(tc.letters, tc.k)
+		if result := buff.String(); result != tc.expected {
+			t.Errorf("Expected \n%s, got \n%s", tc.expected, result)
+		}
+	}
+}
+
+func BenchmarkPrintZigZag(b *testing.B) {
+	// don't run in parallel due to global var
+	buff := new(bytes.Buffer)
+	out = buff
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			PrintZigZag(tc.letters, tc.k)
+		}
+	}
+}