update

005.买汽水.go

@@ -0,0 +1,43 @@
+/*
+
+每瓶汽水单价2元
+规则
+	4个瓶盖可以换1瓶汽水
+	2个空瓶可以换1瓶汽水
+
+30元可以喝到多少瓶汽水?
+*/
+
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println(countBottle(30))
+}
+
+func countBottle(n int) int {
+	unitPrice := 2
+
+	lid := n / unitPrice
+	empty := n / unitPrice
+	total := n / unitPrice
+
+	newBottle := 0 // 兑换到的新瓶子
+
+	// 注意准入条件
+	for lid+newBottle >= 4 || empty+newBottle >= 2 {
+		// 1. drink
+		lid += newBottle
+		empty += newBottle
+
+		// 2. 兑换
+		newBottle = lid/4 + empty/2
+		total += newBottle
+
+		lid %= 4
+		empty %= 2
+	}
+
+	return total
+}

151.颠倒字符串中的单词.go

@@ -66,33 +66,42 @@
  */
 package main
 
+import (
+	"strings"
+	"fmt"
+)
+
 func main() {
 	s := "the sky is blue"
-	reverseWords(s)
+	fmt.Println(reverseWords(s))
 }
 
 // @lc code=start
 func reverseWords(s string) string {
 
-	result := []byte{}
+	result := new(strings.Builder)
 
-	for i := len(s) - 1; i >= 0; i-- {
-		ans := []byte{}
-		hasWord := false
-		for i >= 0 && s[i] == byte(' ') {
-			i--
-		}
-		for i >= 0 && s[i] != byte(' ') {
-			hasWord = true
-			ans = append([]byte{s[i]}, ans...)
-			i--
+	i := len(s) - 1
+
+	for i >= 0{
+		j := i
+		for j >= 0 && s[j] == byte(' ') {
+			j--
 		}
-		if hasWord {
-			ans = append(ans, byte(' '))
-			result = append(result, ans...)
+		end := j
+		for j >= 0 && s[j] != byte(' ') {
+			j--
 		}
+		start := j
+
+		result.Write([]byte(s[start+1:end+1]))
+		result.WriteByte(byte(' '))
+
+
+		i = j
 	}
-	return string(result[:len(result)-1])
+	rt := result.String()
+	return string(rt[:len(rt)-1])
 }
 
 // @lc code=end