题解 | #翻转单词序列#
翻转单词序列
https://www.nowcoder.com/practice/3194a4f4cf814f63919d0790578d51f3
1. Java API
import java.util.*; public class Solution { public String ReverseSentence(String str) { int n = str.length(); String[] words = str.split(" "); StringBuilder sb = new StringBuilder(); for(int i = words.length - 1; i >= 0; i --){ sb.append(words[i]).append(" "); } return sb.toString().trim(); } }
2. 双指针算法
public class Solution { public String ReverseSentence(String str) { str = str.trim(); // 删除首尾空格 int j = str.length() - 1, i = j; StringBuilder res = new StringBuilder(); while(i >= 0) { while(i >= 0 && str.charAt(i) != ' ') i--; // 搜索首个空格 res.append(str.substring(i + 1, j + 1) + " "); // 添加单词 while(i >= 0 && str.charAt(i) == ' ') i--; // 跳过单词间空格 j = i; // j 指向下个单词的尾字符 } return res.toString().trim(); // 转化为字符串并返回 } }