Difficulty:easy
More:【目录】LeetCode Java实现
Description
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"]
Intuition
use a pointer
Solution
public void reverseString(char[] s) {
for(int i=0; i<s.length/2; i++){
char temp = s[i];
s[i] = s[s.length-1-i];
s[s.length-1-i]=temp;
}
}
Complexity
Time complexity : O(n)
Space complexity : O(1)
More:【目录】LeetCode Java实现