求教 557. Reverse Words in a String III，使用 C 语言写..

[nomemo]

Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Example 1:

Input: "Let's take LeetCode contest"
Output: "s'teL ekat edoCteeL tsetnoc"

Note: In the string, each word is separated by single space and there will not be any extra space in the string.

地址： https://leetcode.com/problems/reverse-words-in-a-string-iii/#/description

不使用额外空间，但 c 的字符串不应该是常量不可修改嘛？

为何我看别人写的都是直接对字条串的单个字符进行修改呢

void reverse(int b, int e, char *s){
    while(b < e) {
        s[b] = s[b] ^ s[e];
        s[e] = s[b] ^ s[e];
        s[b] = s[b] ^ s[e];
        b++;
        e--;
    }
}

char* reverseWords(char* s) {
    int i, s_len = strlen(s), index = 0;
    
    for(i = 0; i <= s_len; i++) {
        if((s[i] == ' ') || (s[i] == '\0')){
            reverse(index, i - 1, s);
            index = i + 1;
        }
    }
    return s;
}

[bombless]

是字面量对应的匿名数组不可写而已。
其实是一个运行时行为，和常量什么的就没啥关系了

[Mirana]

传进来的不是常量啊

[mason961125]

C 什么时候不许改字符串了？和 Python 搞混了？

[skydiver]

用异或做交换的直接 pass

[mrvon]

你仔细看，这个是
char* s
而不是
const char* s

[nomemo]

@bombless
@Mirana
@mrvon

感谢，明白了


@skydiver

请指教原因？

[si]

char *testInput = "Let's take LeetCode contest"; 这种是定义 char 指针，指针指向 "Let's take LeetCode contest"，一般编译器会把 "Let's take LeetCode contest" 放到常量段。一般常量段是只读的，如果对它写入，就会崩溃。

char testInput[] = "Let's take LeetCode contest"; 这样是定义一个 char 数组，并把"Let's take LeetCode contest"拷贝到数组里面。数组是允许读写的。

[ryd994]

任何\0 结尾的 char[] 都是 C-string

[demerol]

现在的 gcc 貌似 xor 的速度不如加个 temp