Add solution and test-cases and README for problem 6

Author: 0xff-dev

leetcode/1-100/0006.ZigZag-Conversion/README.md

@@ -0,0 +1,51 @@
+# [6.Zigzag Conversion][title]
+
+## Description
+The string `"PAYPALISHIRING"` is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)  
+
+```shell
+P   A   H   N
+A P L S I I G
+Y   I   R
+```
+
+And then read line by line: `"PAHNAPLSIIGYIR"`
+
+Write the code that will take a string and make this conversion given a number of rows:
+
+```shell
+string convert(string s, int numRows);
+```
+
+**Example 1:**
+
+```
+Input: s = "PAYPALISHIRING", numRows = 3
+Output: "PAHNAPLSIIGYIR"
+```
+
+**Example 2:**
+
+```
+Input: s = "PAYPALISHIRING", numRows = 4
+Output: "PINALSIGYAHRPI"
+Explanation:
+P     I    N
+A   L S  I G
+Y A   H R
+P     I
+```
+
+**Example 3:**
+
+```
+Input: s = "A", numRows = 1
+Output: "A"
+
+```
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-algorithm][me]
+
+[title]: https://leetcode.com/problems/zigzag-conversion/
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/1-100/0006.ZigZag-Conversion/Solution.go

@@ -1,6 +1,9 @@
 package Solution
 
-import "fmt"
+import (
+	"bytes"
+	"fmt"
+)
 
 func convert(s string, numRows int) string {
 	if numRows == 1 || numRows <= 0 || numRows > len(s) {
@@ -53,3 +56,26 @@ func convert2(s string, numRows int) string {
 	}
 	return string(result)
 }
+
+func convert3(s string, numRows int) string {
+	buf := bytes.NewBufferString("")
+	if numRows == 1 {
+		return s
+	}
+
+	width := 2 * (numRows - 1)
+	for idx := 0; idx < numRows; idx++ {
+		step := 2 * idx
+		if idx == 0 || idx == numRows-1 {
+			step = width
+		}
+		for walker := idx; walker < len(s); walker += step {
+			buf.WriteByte(s[walker])
+			if step != width {
+				step = width - step
+			}
+		}
+	}
+
+	return buf.String()
+}

leetcode/1-100/0006.ZigZag-Conversion/Solution_test.go

@@ -15,6 +15,7 @@ func TestSolution(t *testing.T) {
 	}{
 		{"1 test 1", "PAYPALISHIRING", 3, "PAHNAPLSIIGYIR"},
 		{"2 test 2", "PAYPALISHIRING", 4, "PINALSIGYAHRPI"},
+		{"3 test 3", "A", 1, "A"},
 	}
 
 	//	开始测试
@@ -25,6 +26,16 @@ func TestSolution(t *testing.T) {
 				t.Fatalf("expected: %v, but got: %v, with inputs: %v-%v",
 					c.expect, ret, c.input1, c.input2)
 			}
+			ret = convert2(c.input1, c.input2)
+			if !reflect.DeepEqual(ret, c.expect) {
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v-%v",
+					c.expect, ret, c.input1, c.input2)
+			}
+			ret = convert3(c.input1, c.input2)
+			if !reflect.DeepEqual(ret, c.expect) {
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v-%v",
+					c.expect, ret, c.input1, c.input2)
+			}
 		})
 	}
 }