反转字符串中单词的顺序

Question

我有这个string s1 = "My name is X Y Z",我想扭转这些词的顺序s1 = "Z Y X is name My".

我可以使用额外的数组来做到这一点.我认为很难,但有可能在现场(不使用额外的数据结构)并且时间复杂度为O(n)吗？

Answer 1

反转整个字符串,然后反转每个单词的字母.

第一次传递后,字符串将是

s1 = "Z Y X si eman yM"

在第二次通过后,它将是

s1 = "Z Y X is name My"

Answer 2

将字符串反转,然后在第二遍中反转每个字......

在c#中,完全就地没有其他数组:

static char[] ReverseAllWords(char[] in_text)
{
    int lindex = 0;
    int rindex = in_text.Length - 1;
    if (rindex > 1)
    {
        //reverse complete phrase
        in_text = ReverseString(in_text, 0, rindex);

        //reverse each word in resultant reversed phrase
        for (rindex = 0; rindex <= in_text.Length; rindex++)
        {
            if (rindex == in_text.Length || in_text[rindex] == ' ')
            {
                in_text = ReverseString(in_text, lindex, rindex - 1);
                lindex = rindex + 1;
            }
        }
    }
    return in_text;
}

static char[] ReverseString(char[] intext, int lindex, int rindex)
{
    char tempc;
    while (lindex < rindex)
    {
        tempc = intext[lindex];
        intext[lindex++] = intext[rindex];
        intext[rindex--] = tempc;
    }
    return intext;
}

Answer 3

Not exactly in place, but anyway: Python:

>>> a = "These pretzels are making me thirsty"
>>> " ".join(a.split()[::-1])
'thirsty me making are pretzels These'

Answer 4

在Smalltalk中:

'These pretzels are making me thirsty' subStrings reduce: [:a :b| b, ' ', a]

我知道没有人关心Smalltalk,但它对我来说太美了.