[LeetCode] 344. Reverse String

Write a function that reverses a string. The input string is given as an array of characters s.

You must do this by modifying the input array in-place with O(1) extra memory.

Example 1:

Input: s = ["h","e","l","l","o"]
Output: ["o","l","l","e","h"]

Example 2:

Input: s = ["H","a","n","n","a","h"]
Output: ["h","a","n","n","a","H"]

Constraints:

• 1 <= s.length <= 105
• s[i] is a printable ascii character.

反转字符串。

题目既是题意。思路很简单，two pointer 两边往中间逼近做法。

时间O(n)

空间O(1) - 这也是题目要求

Java实现

class Solution {
    public void reverseString(char[] s) {
        int i = 0;
        int j = s.length - 1;
        while (i < j) {
            char temp = s[i];
            s[i] = s[j];
            s[j] = temp;
            i++;
            j--;
        }
    }
}

 

JavaScript实现

/**
 * @param {character[]} s
 * @return {void} Do not return anything, modify s in-place instead.
 */
var reverseString = function(s) {
    let left = 0;
    let right = s.length - 1;
    while (left < right) {
        let temp = s[left];
        s[left] = s[right];
        s[right] = temp;
        left++;
        right--;
    }
};

 

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LeetCode 题目总结