C++博客-三少爷-随笔分类-the c programming language

quick sort

三少_爷 — Mon, 28 May 2012 13:26:00 GMT

  1 #include
  2
  3 int partition(int a[],int low,int high)
  4 {
  5         int pivotkey = a[low];
  6         a[0] = a[low];
  7         while( low < high)
  8         {
  9                 while(low < high && a[high] >= pivotkey)
10                         --high;
11                 a[low] = a[high];
12                 while(low < high && a[low] <= pivotkey)
13                         ++low;
14                 a[high] = a[low];
15         }
16         a[low] = a[0];
17         return low;
18 }
19
20 void qsort(int a[],int low,int high)
21 {
22         int pivotkey;
23         if(low < high){
24                 pivotkey = partition(a,low,high);
25                 qsort(a,low,pivotkey - 1);
26                 qsort(a,pivotkey + 1,high);
27         }
28 }
29
30 void main()
31 {
32         int i;
33         int a[10] = {0,6,5,4,23,54,12,56,87,10};
34         qsort(a,1,9);
35         for(i = 1;i<=9;i++)
36                 printf("%3d",a[i]);
37         printf("\n");
38 }

三少_爷 2012-05-28 21:26 发表评论

binary tree

三少_爷 — Sun, 27 May 2012 07:45:00 GMT

  1 #include
  2 #include
  3
  4 typedef struct tnode{
  5         int data;
  6         struct tnode *left;
  7         struct tnode *right;
  8 }tnode,*tree;
  9
10 void createtree(tree *t,int d){
11         tnode *tn=(tnode *)malloc(sizeof(tnode));
12         tnode ** root;
13         (*tn).data = d;
14         (*tn).right = 0;
15         (*tn).left = 0;
16         if(!(*t)){
17                 *t = tn;
18                 root = *t;
19         }
20         else{
21         root = *t;
22                 while(1){
23                         if((**t).data < d){
24                                 if((**t).right){
25                                         *t = (**t).right;
26                                         continue;
27                                 }
28                                 else{
29                                         (**t).right = tn;
30                                         break;
31                                 }
32                         }
33                         else if((**t).data >= d){
34                                 if((**t).left){
35                                         *t =(**t).left;
36                                         continue;
37                                 }
38                                 else{
39                                         (**t).left = tn;
40                                         break;

41                                 }
42                         }
43                 }
44         }
45         *t = root;
46 }
47 void inorder(tree t)
48 {
49         if(t){
50                 inorder((*t).left);
51                 printf("%d\n",(*t).data);
52                 inorder((*t).right);
53         }
54 }
55 void main()
56 {
57         int i;
58         tree t=0;
59         printf("input number:0 exit\n");
60         scanf("%d",&i);
61         while(i != 0){
62                 createtree((&t),i);
63                 scanf("%d",&i);
64         }
65         printf("the data is:\n");
66         inorder(t);
67         printf("\n");
68 }

三少_爷 2012-05-27 15:45 发表评论

binary search

三少_爷 — Sun, 20 May 2012 14:07:00 GMT

  1 #include
  2
  3 int bi_search(int x,int a[],int n)
  4 {
  5         int low,upper,mid;
  6
  7         low = 0;
  8         upper = n-1;
  9         while(low <= upper)
10         {
11                 mid = (low + upper)/2;
12                 if(x < a[mid])
13                         upper = mid-1;
14                 else if(x > a[mid])
15                         low = mid+1;
16                 else return mid;
17         }
18         return -1;
19 }
20
21 void main()
22 {
23         int a[5] = {3,4,5,6,7};
24         printf("%d\n",bi_search(4,a,5));
25 }

三少_爷 2012-05-20 22:07 发表评论

convert string to numeric

三少_爷 — Sun, 20 May 2012 11:38:00 GMT

  1 #include
  2
  3 int atoi(char s[])
  4 {
  5         int i,n;
  6
  7         for( i = 0,n=0; s[i] >= '0' && s[i] <='9'; i++)
  8         {
  9                 n = n * 10 + s[i] - '0';
10         }
11         return n;
12 }
13
14 void main()
15 {
16         char a[] = "1234";
17         printf("%d\n",atoi(a));
18 }

三少_爷 2012-05-20 19:38 发表评论

longest line

三少_爷 — Sun, 20 May 2012 06:27:00 GMT

  1 #include
  2 #define MAXLINE 1000
  3
  4 int get_line(char line[],int maxline);
  5 void c_line(char to[],char from[]);
  6
  7 void main()
  8 {
  9         int len;
10         int max;
11         char line[MAXLINE];
12         char longest[MAXLINE];
13
14         max = 0;
15         while((len = get_line(line,MAXLINE)) > 0)
16         {
17                 if(len > max)
18                 {
19                         max = len;
20                         c_line(longest,line);
21                 }
22         }
23         if(max > 0)
24                 printf("%s\n",longest);
25         return 0;
26 }
27
28 int get_line(char s[],int lim)
29 {
30         int c,i;
31         for(i = 0; i < lim - 1 && ((c = getchar()) != EOF ) && c != '\n';i++)
32                         s[i] = c;
33         if(c == '\n')
34         {
35                 s[i] = c;
36                 ++i;
37         }
38         s[i] = '\0';
39         return i;
40
41 }
42
43 void c_line(char to[],char from[])
44 {
45         int i;
46
47         i = 0;
48         while(to[i] = from[i])
49                 i++;
50 }

三少_爷 2012-05-20 14:27 发表评论

word counting

三少_爷 — Sat, 19 May 2012 14:33:00 GMT

  1 #include
  2
  3 #define IN 1
  4 #define OUT 0
  5
  6 void main()
  7 {
  8         int nw,state;
  9         char c;
10
11         nw = 0;
12         state = OUT;
13
14         while((c = getchar()) != EOF)
15         {
16                 if( (c == ' ') || (c == '\t') || (c == '\n'))
17                         state = OUT;
18                 else if(state == OUT){
19                         state = IN;
20                         ++nw;
21                 }
22         }
23         printf("%d\n",nw);
24 }

三少_爷 2012-05-19 22:33 发表评论

character counting

三少_爷 — Sat, 19 May 2012 14:08:00 GMT

  1 #include
  2
  3 void main()
  4 {
  5         int nc;
  6
  7         nc = 0;
  8         while(getchar() != EOF)
  9         {
10                 nc++;
11         }
12         printf("%d\n",nc);
13 }

三少_爷 2012-05-19 22:08 发表评论

file copying

三少_爷 — Sat, 19 May 2012 13:58:00 GMT

  1 #include
  2
  3 void main()
  4 {
  5         char c;
  6
  7         while((c = getchar()) != EOF)
  8         {
  9                 putchar(c);
10         }
11
12 }

三少_爷 2012-05-19 21:58 发表评论