add 482 166 405

Author: edboffical

convert-a-number-to-hexadecimal.go

@@ -0,0 +1,21 @@
+package main
+
+// 405 https://leetcode-cn.com/problems/convert-a-number-to-hexadecimal/
+// 进制转换
+func toHex(num int) string {
+	if num == 0 {
+		return "0"
+	}
+	arr := make([]byte, 0, 8)
+	for i := 7; i >= 0; i-- {
+		n := byte(num >> (4 * i) & 0xf)
+		if n > 0 || len(arr) > 0 {
+			if n < 10 {
+				arr = append(arr, n+'0')
+			} else {
+				arr = append(arr, n-10+'a')
+			}
+		}
+	}
+	return string(arr)
+}

faction-to-recurring-decimal.go

@@ -0,0 +1,95 @@
+package main
+
+import "strconv"
+
+// 166 https://leetcode-cn.com/problems/fraction-to-recurring-decimal/
+// 除法模拟
+func fractionToDecimal(numerator int, denominator int) string {
+	result := ""
+	flag := "" // 符号位
+	// 将符号位和数字分离开
+	if denominator == 0 {
+		return ""
+	}
+	if numerator == 0 {
+		return "0"
+	}
+	if numerator*denominator > 0 {
+		flag = ""
+		if numerator < 0 {
+			numerator = numerator * (-1)
+			denominator = denominator * (-1)
+		}
+	} else {
+		if numerator > 0 {
+			flag = "-"
+			denominator = denominator * (-1)
+		} else {
+			flag = "-"
+			numerator = numerator * (-1)
+		}
+	}
+	if (numerator % denominator) == 0 {
+		return flag + strconv.Itoa(numerator/denominator)
+	} else {
+		// 定义整数和小数
+		integer := 0
+		// 若是被除数 > 除数，则算出商的整数部分
+		for i := 1; numerator > i*denominator; i++ {
+			integer++
+		}
+		result += strconv.Itoa(integer)
+		result += "."
+		numerator -= integer * denominator
+		// 现在，被除数小于除数了，商的整数部分也算出来了，该算小数部分了
+		hashMap := make(map[int]int) // 用于记录余数出现的位置，key是数字，value是其在quotient数组里的index
+		var quotient []int           // 用于记录每次出现的小数部分商
+		j := 0
+		for numerator%denominator != 0 {
+			if numerator < denominator {
+				numerator *= 10
+			}
+			quotientRes := numerator / denominator
+			numerator %= denominator
+			if _, ok := hashMap[numerator]; !ok {
+				// 表明没有循环，保存商和余数
+				quotient = append(quotient, quotientRes)
+				hashMap[numerator] = j
+				j++
+			} else {
+				// 表明有循环
+				if quotient[hashMap[numerator]] == quotientRes {
+					for k := 0; k < hashMap[numerator] && k < len(quotient); k++ {
+						result += strconv.Itoa(quotient[k])
+					}
+					result += "("
+					for k := hashMap[numerator]; k < len(quotient); k++ {
+						result += strconv.Itoa(quotient[k])
+					}
+					result += ")"
+				} else {
+					// 下面这段代码用于防止1/6这种情况的出现，即：余数重复出现，不一定代表就此循环
+					for k := 0; k <= hashMap[numerator] && k < len(quotient); k++ {
+						result += strconv.Itoa(quotient[k])
+					}
+					result += "("
+					for k := hashMap[numerator] + 1; k < len(quotient); k++ {
+						result += strconv.Itoa(quotient[k])
+					}
+					result += strconv.Itoa(quotientRes)
+					result += ")"
+				}
+				break
+			}
+			// 表明除尽了
+			if numerator == 0 {
+				for _, item := range quotient {
+					result += strconv.Itoa(item)
+				}
+				break
+			}
+		}
+	}
+	result = flag + result
+	return result
+}

license-key-formatting.go

@@ -0,0 +1,21 @@
+package main
+
+import "strings"
+
+// 482 https://leetcode-cn.com/problems/license-key-formatting/
+func licenseKeyFormatting(s string, k int) string {
+	s = strings.ReplaceAll(s, "-", "")
+	if s == "" {
+		return ""
+	}
+	firstCount := len(s) % k
+	if firstCount == 0 {
+		firstCount = k
+	}
+	var res = []string{s[:firstCount]}
+
+	for i := 0; i < (len(s)-firstCount)/k; i++ {
+		res = append(res, s[firstCount+i*k:firstCount+(i+1)*k])
+	}
+	return strings.ToUpper(strings.Join(res, "-"))
+}