344.反转字符串.md

344. 反转字符串

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题目

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 char[] 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。

你可以假设数组中的所有字符都是 ASCII 码表中的可打印字符。

输入：["h","e","l","l","o"]
输出：["o","l","l","e","h"]
输入：["H","a","n","n","a","h"]
输出：["h","a","n","n","a","H"]

方法

code

js

let reverseString = s => {
    let swap = (s, i, j) => {
        let temp = s[i];
        s[i] = s[j];
        s[j] = temp;
    };
    let p1 = 0, p2 = s.length - 1;
    while (p1 < p2) {
        swap(s, p1++, p2--);
    }
    return s;
};
console.log(reverseString(["h","e","l","l","o"]))

go

func reverseString(s []byte) {
	swap := func (s []byte, i, j int) {
		temp := s[i]
		s[i] = s[j]
		s[j] = temp
	}
	p1, p2 := 0, len(s) - 1
	for p1 < p2 {
		swap(s, p1, p2)
		p1++
		p2--
	}
	fmt.Println(s)
}

java

class Solution {
    public void reverseString(char[] s) {
        int p1 = 0, p2 = s.length - 1;
        while(p1 < p2 ){
            swap(s, p1++, p2--);
        }
    }
    public void swap(char[] s, int i, int j) {
        char temp = s[i];
        s[i] = s[j];
        s[j] = temp;
    }
}