面試系列5以單詞為最小單位翻轉(zhuǎn)字符串-改進版-

原題：
     以單詞為最小單位翻轉(zhuǎn)字符串
     write the function string reversestringwordbyword(string input) that reverses
     a string word by word. for instance,
     reversestringwordbyword('the house is blue') --> 'blue is house the'
     reversestringwordbyword('zed is dead') --> 'dead is zed'
     reversestringwordbyword('all-in-one') --> 'all-in-one'
    面試系列4種的實現(xiàn)，比較費空間，因為多申請了一段空間來保存結(jié)果。
    在看了其他高手的實現(xiàn)后，發(fā)現(xiàn)可以不用申請空間，并且循環(huán)的次數(shù)更少，也可以實現(xiàn)相同的效果。
    大體思路是：
    原字符串： the house is blue
    先翻轉(zhuǎn)整個字符串-> eulb si esuoh eht
    再翻轉(zhuǎn)單個單詞。
    代碼：
    /********************************************************************
     created: 2006/06/16
     filename: c:/documents and settings/administrator/桌面/flwo/reverse2.c
     file path: c:/documents and settings/administrator/桌面/flwo
     file base: reverse
     file ext: c
     author: a.tng
     version: 0.0.1
     purpose: 以單詞為最小單位翻轉(zhuǎn)字符串-2 優(yōu)化版
     write the function string reversestringwordbyword(string input)
     that reverses a string word by word. for instance,
     reversestringwordbyword('the house is blue') --> 'blue is house the'
     reversestringwordbyword('zed is dead') --> 'dead is zed'
     reversestringwordbyword('all-in-one') --> 'all-in-one'
     參考其他高手的思路：
     先翻轉(zhuǎn)整個字符串-> eulb si esuoh eht
     再翻轉(zhuǎn)單個單詞。
    *********************************************************************/
    #include
    #include
    #include
    #define reverse_word(p1, p2) while (p1 <= p2) /
     { /
     char ch; /
     ch = *p1; *p1 = *p2; *p2 = ch; /
     p1++; p2--; /
     }
    /*
     * name: reverse_src_word_by_word
     * params:
     * des [out] 輸出字符串， des 指向?qū)崿F(xiàn)申請的空間
     * src [in] 輸入字符串，需要處理的字符串
     * return:
     * 處理完成后的 des 指針
     * notes:
     * 以單詞為最下單位翻轉(zhuǎn)字符串
     * 優(yōu)化： 先翻轉(zhuǎn)整個字符串，再翻轉(zhuǎn)單個單詞
     *
     * author: a.tng 2006/06/16 10:37
     */
    char * reverse_str_word_by_word2(char *src)
    {
     char *p1, *p2;
     int n_src_len;
     if (null == src)
     return null;
     /* 先把整個字符串翻轉(zhuǎn)一次 */
     n_src_len = strlen(src);
     p1 = src; p2 = src + n_src_len - 1;
     reverse_word(p1, p2);
    #if 0
     while (p1 <= p2)
     {
     /* 交換頭字符和尾字符 */
     char ch;
     ch = *p1; *p1 = *p2; *p2 = ch;
     p1++; p2--;
     }
    #endif
     /* 再翻轉(zhuǎn)單個單詞 */
     p1 = src; p2 = p1;
     while ('/0' != *p2)
     {
     if (' ' == *p2)
     {
     char *p;
     p = p2 - 1;
     reverse_word(p1, p);
    #if 0
     while (p1 <= p)
     {
     char ch;
     ch = *p1; *p1 = *p; *p = ch;
     p1++; p--;
     }
    #endif
     p2++;
     p1 = p2;
     }
     else
     {
     p2++;
     }
     }
     /* 翻轉(zhuǎn)最后一個單詞 */
     p2--;
     reverse_word(p1, p2);
    #if 0
     while (p1 <= p2)
     {
     char ch;
     ch = *p1; *p1 = *p2; *p2 = ch;
     p1++; p2--;
     }
    #endif
     return src;
    }
    /*
     * name: main
     * params:
     * none
     * return:
     * none
     * notes:
     * none
     *
     * author: a.tng 2006/06/16 10:37
     */
    int main()
    {
     // char src[] = ' all-in-one ';
     // char src[] = 'the house is blue';
     char src[] = 'zed is dead';
     (void) reverse_str_word_by_word2(src);
     printf('*****%s*****/n', src);
     system('pause');
    }