Here is the source code of the C++ program to display the sorted triply linked list by travelling head first and tail first. This C++ program is successfully compiled and run on Dev Cpp, a C++ compiler. The program output is given below.

1. #include<stdio.h>

2. #include<conio.h>

3. #include<iostream.h>

4. using namespace std;

5. int z = 0;

6. struct node

7. {

8.     node *next, *prev, *top;

9.     int data;

10. }*head = NULL, *tail = NULL, *p = NULL, *r = NULL, *np = NULL, *q = NULL;

11. void create(int x)

12. {

13.     np = new node;

14.     np->data = x;

15.     np->next = NULL;

16.     np->prev = NULL;

17.     np->top = NULL;

18.     if (z == 0)

19.     {

20.         tail = np;

21.         head = np;

22.         p = head;

23.         p->next = NULL;

24.         p->prev = NULL;

25.         p->top = NULL;

26.         z++;

27.     }

28.     else

29.     {

30.         p = head;

31.         r = p;

32.         if (np->data < p->data)

33.         {

34.             np->next = p;

35.             p->prev = np;

36.             np->prev = NULL;

37.             head = np;

38.             p = head;

39.             do

40.             {

41.                 p = p->next;

42.             }

43.             while (p->next != NULL);

44.             tail = p;

45.         }

46.         else if (np->data > p->data)

47.         {

48.             while (p != NULL && np->data > p->data)

49.             {

50.                 r = p;

51.                 p = p->next;

52.                 if (p == NULL)

53.                 {

54.                     r->next = np;

55.                     np->prev = r;

56.                     np->next = NULL;

57.                     tail = np;

58.                     break;

59.                 }   

60.                 else if (np->data <= p->data)

61.                 {

62.                     if (np->data < p->data)

63.                     { 

64.                         r->next = np;

65.                         np->prev = r;

66.                         np->next = p;

67.                         p->prev = np;

68.                         if (p->next != NULL)

69.                         {

70.                             do

71.                             {

72.                                 p = p->next;

73.                             }

74.                         while (p->next !=NULL);

75.                     }

76.                     tail = p;

77.                     break;

78.                     }

79.                     else if (p->data == np->data)

80.                     {

81.                         q = p;

82.                         while (q->top != NULL)

83.                         {

84.                            q = q->top;

85.                         }

86.                         q->top = np;

87.                         np->top = NULL;

88.                         break;

89.                     }

90.                 }

91.             }

92.         }        

93.     }

94. }

95. void traverse_tail()

96. {

97.     node *t = tail;

98.     //cout<<"\n\nlinear display of nodes currently present in linked list....\n\n";

99.     while (t != NULL)

100.     {

101.         cout<<t->data<<"\t";

102.         q = t;

103.         while (q->top != NULL)

104.         {

105.               q = q->top;

106.               cout<<"top->"<<q->data<<"\t";

107.         }

108.         t = t->prev;

109.     }

110.     cout<<endl;

111. }

112. void traverse_head()

113. {

114.     node *t = head;

115.     while (t != NULL)

116.     {

117.         cout<<t->data<<"\t";

118.         q = t;

119.         while (q->top != NULL)

120.         {

121.             q = q->top; 

122.             cout<<"top->"<<q->data<<"\t";

123.         }

124.         t = t->next;

125.     }

126.     cout<<endl;

127. }

128. int main()

129. {

130.     int i = 0, n, x, ch;

131.     cout<<"Enter the no of nodes\n";

132.     cin>>n;

133.     while (i < n)

134.     {

135.         cout<<"\nEnter value of node\n";

136.         cin>>x;

137.         create(x);

138.         i++;

139.     }

140.     cout<<"\nTraversing Doubly Linked List head first\n";

141.     traverse_head();

142.     cout<<"\nTraversing Doubly Linked List tail first\n";

143.     traverse_tail();

144.     getch();

145. }

146. Output
      
     enter the no of nodes
     6
      
     enter value of node
     2
      
     enter value of node
     6
      
     enter value of node
     3
      
     enter value of node
     5
      
     enter value of node
     3
      
     enter value of node
     8
      
     Traversing Doubly Linked List head first
     2       3       top->3  5       6       8
      
     Traversing Doubly Linked List tail first
     8       6       5       3       top->3  2