链表思想

 1 #include <stdio.h>

 2  

 3 /* count lines in input */

 4 int

 5 main()

 6 {

 7         int c, pc; /* c = character, pc = previous character */

 8  

 9         /* set pc to a value that wouldn't match any character, in case

10         this program is ever modified to get rid of multiples of other

11         characters */

12  

13         pc = EOF;

14  

15         while ((c = getchar()) != EOF) {

16                 if (c == ' ')

17                         if (pc != ' ')   /* or if (pc != c) */ 

18                                 putchar(c);

19  

20                 /* We haven't met 'else' yet, so we have to be a little clumsy */

21                 if (c != ' ')

22                         putchar(c);

23                 pc = c;

24         }

25  

26         return 0;

27 }

PS：   PC 模拟 C前一个节点！