344. Reverse String (Easy)
https://leetcode.com/problems/reverse-string/
Write a function that reverses a string. The input string is given as an array of characters char[]
.
Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.
You may assume all the characters consist of printable ascii characters.
Example 1:
Input: ["h","e","l","l","o"] Output: ["o","l","l","e","h"]
Example 2:
Input: ["H","a","n","n","a","h"] Output: ["h","a","n","n","a","H"]
Solutions
class Solution {
public void reverseString(char[] s) {
if (s == null || s.length <= 1) {
return;
}
int lptr = 0;
int rptr = s.length - 1;
while (lptr < rptr) {
swap(s, lptr, rptr);
lptr++;
rptr--;
}
}
private void swap(char[] s, int x, int y) {
char tmp = s[x];
s[x] = s[y];
s[y] = tmp;
}
}