规范格式

leetcode/0089.Gray-Code/89. Gray Code.go

@@ -0,0 +1,63 @@
+package leetcode
+
+// 解法一 递归方法，时间复杂度和空间复杂度都较优
+func grayCode(n int) []int {
+	if n == 0 {
+		return []int{0}
+	}
+	res := []int{}
+	num := make([]int, n)
+	generateGrayCode(int(1<<uint(n)), 0, &num, &res)
+	return res
+}
+
+func generateGrayCode(n, step int, num *[]int, res *[]int) {
+	if n == 0 {
+		return
+	}
+	*res = append(*res, convertBinary(*num))
+
+	if step%2 == 0 {
+		(*num)[len(*num)-1] = flipGrayCode((*num)[len(*num)-1])
+	} else {
+		index := len(*num) - 1
+		for ; index >= 0; index-- {
+			if (*num)[index] == 1 {
+				break
+			}
+		}
+		if index == 0 {
+			(*num)[len(*num)-1] = flipGrayCode((*num)[len(*num)-1])
+		} else {
+			(*num)[index-1] = flipGrayCode((*num)[index-1])
+		}
+	}
+	generateGrayCode(n-1, step+1, num, res)
+	return
+}
+
+func convertBinary(num []int) int {
+	res, rad := 0, 1
+	for i := len(num) - 1; i >= 0; i-- {
+		res += num[i] * rad
+		rad *= 2
+	}
+	return res
+}
+
+func flipGrayCode(num int) int {
+	if num == 0 {
+		return 1
+	}
+	return 0
+}
+
+// 解法二 直译
+func grayCode1(n int) []int {
+	var l uint = 1 << uint(n)
+	out := make([]int, l)
+	for i := uint(0); i < l; i++ {
+		out[i] = int((i >> 1) ^ i)
+	}
+	return out
+}

leetcode/0089.Gray-Code/89. Gray Code_test.go

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+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question89 struct {
+	para89
+	ans89
+}
+
+// para 是参数
+// one 代表第一个参数
+type para89 struct {
+	one int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans89 struct {
+	one []int
+}
+
+func Test_Problem89(t *testing.T) {
+
+	qs := []question89{
+
+		question89{
+			para89{2},
+			ans89{[]int{0, 1, 3, 2}},
+		},
+
+		question89{
+			para89{0},
+			ans89{[]int{0}},
+		},
+
+		question89{
+			para89{3},
+			ans89{[]int{0, 1, 3, 2, 6, 7, 5, 4}},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 89------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans89, q.para89
+		fmt.Printf("【input】:%v       【output】:%v\n", p, grayCode(p.one))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/0089.Gray-Code/README.md

@@ -0,0 +1,46 @@
+# [89. Gray Code](https://leetcode.com/problems/gray-code/)
+
+## 题目
+
+The gray code is a binary numeral system where two successive values differ in only one bit.
+
+Given a non-negative integer *n* representing the total number of bits in the code, print the sequence of gray code. A gray code sequence must begin with 0.
+
+**Example 1:**
+
+    Input: 2
+    Output: [0,1,3,2]
+    Explanation:
+    00 - 0
+    01 - 1
+    11 - 3
+    10 - 2
+    
+    For a given n, a gray code sequence may not be uniquely defined.
+    For example, [0,2,3,1] is also a valid gray code sequence.
+    
+    00 - 0
+    10 - 2
+    11 - 3
+    01 - 1
+
+**Example 2:**
+
+    Input: 0
+    Output: [0]
+    Explanation: We define the gray code sequence to begin with 0.
+                 A gray code sequence of n has size = 2n, which for n = 0 the size is 20 = 1.
+                 Therefore, for n = 0 the gray code sequence is [0].
+
+
+## 题目大意
+
+格雷编码是一个二进制数字系统，在该系统中，两个连续的数值仅有一个位数的差异。给定一个代表编码总位数的非负整数 n，打印其格雷编码序列。格雷编码序列必须以 0 开头。
+
+
+
+## 解题思路
+
+- 输出 n 位格雷码
+- 格雷码生成规则：以二进制为0值的格雷码为第零项，第一次改变最右边的位元，第二次改变右起第一个为1的位元的左边位元，第三、四次方法同第一、二次，如此反复，即可排列出 n 个位元的格雷码。
+- 可以直接模拟，也可以用递归求解。