Merge pull request #585 from openset/develop

Add: ZigZag Conversion

Author: Shuo

Diff for: problems/zigzag-conversion/zigzag_conversion.go

@@ -1 +1,20 @@
 package zigzag_conversion
+
+func convert(s string, numRows int) string {
+	l := len(s)
+	if l <= numRows || numRows < 2 {
+		return s
+	}
+	ans, col := make([]byte, 0, l), (l-1)/(numRows-1)
+	for r := 0; r < numRows; r++ {
+		for c := 0; c <= col; c++ {
+			if c&1 == 0 || r > 0 && r < numRows-1 {
+				k := (numRows-1)*(c+c&1) + r*(1-c&1*2)
+				if k < l {
+					ans = append(ans, s[k])
+				}
+			}
+		}
+	}
+	return string(ans)
+}

Diff for: problems/zigzag-conversion/zigzag_conversion_test.go

@@ -1 +1,35 @@
 package zigzag_conversion
+
+import "testing"
+
+type caseType struct {
+	input    string
+	numRows  int
+	expected string
+}
+
+func TestConvert(t *testing.T) {
+	tests := [...]caseType{
+		{
+			input:    "PAYPALISHIRING",
+			numRows:  3,
+			expected: "PAHNAPLSIIGYIR",
+		},
+		{
+			input:    "PAYPALISHIRING",
+			numRows:  4,
+			expected: "PINALSIGYAHRPI",
+		},
+		{
+			input:    "AB",
+			numRows:  1,
+			expected: "AB",
+		},
+	}
+	for _, tc := range tests {
+		output := convert(tc.input, tc.numRows)
+		if output != tc.expected {
+			t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)
+		}
+	}
+}