Add solution and test-cases for problem 405

leetcode/401-500/0405.Convert-a-Number-to-Hexadecimal/README.md

@@ -1,28 +1,25 @@
 # [405.Convert a Number to Hexadecimal][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
+Given an integer `num`, return a string representing its hexadecimal representation. For negative integers, `two’s complement` method is used.
+
+All the letters in the answer string should be lowercase characters, and there should not be any leading zeros in the answer except for the zero itself.
+
+**Note**: You are not allowed to use any built-in library method to directly solve this problem.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: num = 26
+Output: "1a"
 ```
 
-## 题意
-> ...
+**Example 2**
 
-## 题解
-
-### 思路1
-> ...
-Convert a Number to Hexadecimal
-```go
 ```
-
+Input: num = -1
+Output: "ffffffff"
+```
 
 ## 结语
 

leetcode/401-500/0405.Convert-a-Number-to-Hexadecimal/Solution.go

@@ -1,5 +1,84 @@
 package Solution
 
-func Solution(x bool) bool {
-return x
+func Solution(num int) string {
+n2b := map[int]byte{
+0: '0', 1: '1', 2: '2', 3: '3', 4: '4', 5: '5', 6: '6', 7: '7',
+8: '8', 9: '9', 10: 'a', 11: 'b', 12: 'c', 13: 'd', 14: 'e', 15: 'f',
+}
+if num >= 0 {
+bs := make([]byte, 0)
+for num >= 16 {
+mod := num % 16
+num /= 16
+bs = append(bs, n2b[mod])
+}
+bs = append(bs, n2b[num])
+for s, e := 0, len(bs)-1; s < e; s, e = s+1, e-1 {
+bs[s], bs[e] = bs[e], bs[s]
+}
+return string(bs)
+}
+num = -num
+bs := make([]uint8, 32)
+bs[0] = 1
+end := 31
+for num >= 2 {
+mod := num % 2
+bs[end] = uint8(mod)
+num /= 2
+end--
+}
+bs[end] = uint8(num)
+cf := uint8(1)
+for idx := 31; idx > 0; idx-- {
+bs[idx] ^= uint8(1)
+bs[idx] += cf
+cf = bs[idx] / 2
+bs[idx] %= 2
+}
+power := [4]uint8{1, 2, 4, 8}
+result := make([]byte, 8)
+bsIdx, idx := 7, 31
+for idx > 0 {
+base := uint8(0)
+for i := 0; i < 4; i++ {
+base += bs[idx-i] * power[i]
+}
+result[bsIdx] = n2b[int(base)]
+bsIdx--
+idx -= 4
+}
+// ^=1
+return string(result)
+}
+
+func Solution2(num int) string {
+maxInt := 2147483647 // 2**31-1
+minInt := -maxInt - 1 // -2**31
+compare := 4294967295 // 2**32-1
+if num > maxInt || num < minInt {
+return ""
+}
+if num == 0 {
+return "0"
+}
+if num < 0 {
+num = num + 1 + compare
+}
+numMap := map[int]byte{
+0: '0', 1: '1', 2: '2', 3: '3', 4: '4',
+5: '5', 6: '6', 7: '7', 8: '8', 9: '9',
+10: 'a', 11: 'b', 12: 'c', 13: 'd', 14: 'e',
+15: 'f',
+}
+res := make([]byte, 0)
+for num > 0 {
+remainer := num % 16
+num = num / 16
+res = append(res, numMap[remainer])
+}
+for s, e := 0, len(res)-1; s < e; s, e = s+1, e-1 {
+res[s], res[e] = res[e], res[s]
+}
+return string(res)
 }

leetcode/401-500/0405.Convert-a-Number-to-Hexadecimal/Solution_test.go

@@ -10,12 +10,14 @@ func TestSolution(t *testing.T) {
 //	测试用例
 cases := []struct {
 name string
-inputs bool
-expect bool
+inputs int
+expect string
 }{
-{"TestCase", true, true},
-{"TestCase", true, true},
-{"TestCase", false, false},
+{"TestCase1", 26, "1a"},
+{"TestCase2", -1, "ffffffff"},
+{"TestCase3", -10, "fffffff6"},
+{"TestCase4", -23478, "ffffa44a"},
+{"TestCase5", -2, "fffffffe"},
 }
 
 //	开始测试
@@ -26,6 +28,11 @@ func TestSolution(t *testing.T) {
 t.Fatalf("expected: %v, but got: %v, with inputs: %v",
 c.expect, got, c.inputs)
 }
+got = Solution2(c.inputs)
+if !reflect.DeepEqual(got, c.expect) {
+t.Fatalf("expected: %v, but got: %v, with inputs: %v",
+c.expect, got, c.inputs)
+}
 })
 }
 }