题目描述:
对字符串中的所有单词进行倒排。
说明:
1、每个单词是以26个大写或小写英文字母构成;
2、非构成单词的字符均视为单词间隔符;
3、要求倒排后的单词间隔符以一个空格表示;如果原字符串中相邻单词间有多个间隔符时,倒排转换后也只允许出现一个空格间隔符;
4、每个单词最长20个字母;
Java实现:
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while (sc.hasNext()) {
String sentence = sc.nextLine();
char[] chars = sentence.toCharArray();
for (int i = 0; i < chars.length; i++) {
if (!Character.isLetter(chars[i]))
chars[i] = ' ';
}
sentence = String.valueOf(chars);
sentence = sentence.trim();
chars = sentence.toCharArray();
reverse(chars, 0, chars.length-1);
int l = 0;
for (int i = 0; i < chars.length; i++) {
l = i==0 || !Character.isLetter(chars[i-1]) ? i : l;
if (i == chars.length-1 || !Character.isLetter(chars[i+1])) {
reverse(chars, l , i);
}
}
System.out.println(String.valueOf(chars));
}
}
private static void reverse(char[] chars, int s, int e) {
if (s < e) {
int m = s + (e-s)/2;
while (s <= m) {
char tmp = chars[s];
chars[s] = chars[e];
chars[e] = tmp;
s++;
e--;
}
}
}
}
知识点:
- 非字母的字符均视为分隔符,先都转换为' '
- TODO:目前还不能处理单词间有多个空格的情况