JZ44-翻转单词顺序列
左旋转字符串
https://www.nowcoder.com/practice/12d959b108cb42b1ab72cef4d36af5ec?tpId=13&tags=&title=&diffculty=0&judgeStatus=0&rp=1&tab=answerKey
class Solution2 {
public String ReverseSentence(String str) {
int n = str.length();
char[] chars = str.toCharArray();
int i = 0;
for (int j = 0; j < chars.length; j++) {
if (j == chars.length - 1 || chars[j] == ' ') {
if (chars[j] == ' ') { //如果遇到空格，不反转空格
reverse(chars, i, j - 1);
} else { //如果是结尾了，就要反转该位
reverse(chars, i, j);
}
i = j + 1;
}
}
reverse(chars, 0, n - 1); //最后再翻转一次
return new String(chars);
}
private void reverse(char[] c, int i, int j) {
while (i < j)
swap(c, i++, j--);
}
private void swap(char[] c, int i, int j) {
char t = c[i];
c[i] = c[j];
c[j] = t;
}
} 
