151. Reverse Words in a String

Difficulty: Medium

Given an input string, reverse the string word by word.

Example 1:

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Input: "the sky is blue"
Output: "blue is sky the"

Example 2:

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Input: "  hello world!  "
Output: "world! hello"
Explanation: Your reversed string should not contain leading or trailing spaces.

Example 3:

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Input: "a good   example"
Output: "example good a"
Explanation: You need to reduce multiple spaces between two words to a single space in the reversed string.

Note:

• A word is defined as a sequence of non-space characters.
• Input string may contain leading or trailing spaces. However, your reversed string should not contain leading or trailing spaces.
• You need to reduce multiple spaces between two words to a single space in the reversed string.

Follow up:

For C programmers, try to solve it in-place in O(1) extra space.

解法

¶法一

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void (char *s, char* p){
    int L = p - s;
    for(int i = 0; i < L/2; i++){
        s[i] ^= s[L - i - 1];
        s[L - i - 1] ^= s[i];
        s[i] ^= s[L - i - 1];
    }
}


char * reverseWords(char * s){
    int L = strlen(s);
    int i = 0;
    int j = 0;
    int k;
    char *p;
    
    reverse(s, s+L);
    
    while(s[i] != '