逆转字符串

逆转字符串,但是其中的单词仍然是正序的:

  1. 先逆转整个字符串
  2. 再逆转逆转后的字符数组中组成单词的字符
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public class Test {
public static void main(String[] args) {
System.out.println(reverseWords("How are you!"));
System.out.println(reverseWords("do justice to a dinner"));
System.out.println(reverseWords(""));
System.out.println(reverseWords("A"));
System.out.println(reverseWords("A Biao"));
System.out.println(reverseWords("!A Biao C."));
}
public static String reverseWords(String str) {
int start = 1;
int end = 0;
char[] chs = str.toCharArray();
// [1] 先逆转整个字符串
reverseCharactersInRange(chs, 0, chs.length - 1);
// [2] 再逆转逆转后的字符数组中组成单词的字符
for (int i = 0; i < chs.length; ++i) {
if (Character.isLetter(chs[i])) {
// 找到组成单词的字符的起始和结束位置
if (start > end) {
start = end = i;
} else {
++end;
}
} else {
if (start < end) {
reverseCharactersInRange(chs, start, end);
}
start = chs.length;
}
}
if (start < end) {
reverseCharactersInRange(chs, start, end);
}
return new String(chs);
}
public static void reverseCharactersInRange(char[] chs, int start, int end) {
int times = (end - start + 1) / 2;
for (int i = 0; i < times; ++i) {
char temp = chs[start + i];
chs[start + i] = chs[end - i];
chs[end - i] = temp;
}
}
}