编写一个函数,其作用是将输入的字符串反转过来。输入字符串以字符数组 s
的形式给出。
不要给另外的数组分配额外的空间,你必须原地修改输入数组、使用 O(1) 的额外空间解决这一问题。
示例 1:
输入:s = ["h","e","l","l","o"] 输出:["o","l","l","e","h"]
示例 2:
输入:s = ["H","a","n","n","a","h"] 输出:["h","a","n","n","a","H"]
提示:
-
1 <= s.length <= 105
-
s[i]
都是 ASCII 码表中的可打印字符
解【和反转链表一样、使用双指针、更容易】:
class Solution {
public void reverseString(char[] s) {
int l = 0, r = s.length - 1;
while (l < r) {
char temp = s[l];
s[l] = s[r];
s[r] = temp;
l++;
r--;
}
}
}
异或法反转:
class Solution {
public void reverseString(char[] s) {
int l = 0;
int r = s.length - 1;
while (l < r) {
s[l] ^= s[r]; //构造 a ^ b 的结果,并放在 a 中
s[r] ^= s[l]; //将 a ^ b 这一结果再 ^ b ,存入b中,此时 b = a, a = a ^ b
s[l] ^= s[r]; //a ^ b 的结果再 ^ a ,存入 a 中,此时 b = a, a = b 完成交换
l++;
r--;
}
}
}