C++ Program for Recursion in a Singly Linked List Using a singly linked list, su

Question

C++ Program for Recursion in a Singly Linked List

Using a singly linked list, support the ability to add the following information about an airport: airport code, distance from the last entered airport code to the current one. Provide a sentinel header which represents an element whose value is 'LGA' and whose distance is 0. Allow the user to provide 3 types of input:

1. Enter new airport information

2. Specify an existing airport code and calculate the distance from LGA to the selected airport using recursion.

3. Specify an existing airport code and calculate the distance from LGA to the selected airport by looping thru the nodes in standard fashion.

Explanation / Answer

Answer:

My code is below...took hell lot of time...2 hours not enough to do coding...I tested it , works fine.Here is my code:

#include<iostream.h>
#include<stdio.

h>
#include<string.h>
struct node
{
char apcode[30];
int dis;
struct node *link;
};

class aplist
{
private:
struct node *start;
public:
aplist()
{
start=new node;//(struct node *)malloc(sizeof(struct node));;
strcpy(start->apcode,"LGA");
start->dis=0;
start->link=NULL;
}
void addinfo(char str[],int d);
int srchrec(struct node *t,char str[],int addd);
int srchnor(char str[]);
void freemem();
void view();
};
void aplist::view()
{
struct node *t=start;
cout<<" Aiport code with distances from last node: ";
while(t!=NULL)
{
cout<<" "<<t->apcode<<" "<<t->dis;
t=t->link;
}
}

void aplist::addinfo(char str[],int d)
{
struct node *temp;
temp=new node;//(struct airin *)malloc(sizeof(struct airinfo));
strcpy(temp->apcode,str);
temp->dis=d;
temp->link=NULL;

struct node *t=start;
while(t->link!=NULL)
{
t=t->link;
}
t->link=temp;
}
int aplist::srchrec(struct node *t,char str[],int addd)
{
int res;
//struct node *str;
//cout<<str;
if(strcmpi(start->apcode,str)==0)
{
return 0;
}
if(t==NULL)
{
if(start->link!=NULL)
{
res=srchrec(start->link,str,addd+(start->dis));
}
else
return -1;
}
else //
{
// cout<<t->apcode<<" "<<str;
if(strcmpi(t->apcode,str)==0)
{
// cout<<"True";
return addd+(t->dis);
}
else
{
if(t->link!=NULL)
{
res=srchrec(t->link,str,addd+(t->dis));
}
else
{
return -1;
}
}
}
return res;
}
//}//func end
void aplist::freemem()
{
struct node *t=start,*temp;
while(t!=NULL)
{
temp=t->link;
delete temp;
t=temp;
}
}
int aplist::srchnor(char str[])
{
struct node *t=start;
int lastdis=0;
while(t!=NULL)
{
if(strcmpi(t->apcode,str)==0)
{
return lastdis+(t->dis);
}
lastdis=t->dis;
t=t->link;
}
return -1;
}

int main()
{
int choice;
int dist;
char acode[30],ch,more;
aplist l1;
do
{

cout<<"Enter 1 to input airport info";
cout<<" Enter 2 to input airport code to calc dis from LGA using rec";
cout<<" Enter 3 to input airport code to calc dis from LGA normal";
cout<<" Enter 4 to view the entered airport codes";
cout<<" Enter 5 to exit";
cin>>choice;
switch(choice)
{
case 1:
do
{
cout<<" Add Airport Info ";
cout<<" Enter airport code:";
gets(acode);
cout<<" Enter distance from last airport entered:";
cin>>dist;
l1.addinfo(acode,dist);
cout<<" Do you want to add more airport code(y/n):";
cin>>more;
}while(more=='y'||more=='Y');

break;
case 2:
cout<<" Enter airport code whose dis to be measured from LGA(rec):";
gets(acode);
dist=l1.srchrec(NULL,acode,0);
if(dist==-1)
{
cout<<" No such airport is present";
}
else
{
cout<<" Distance of "<<acode<<" from LGA is "<<dist;
}
break;
case 3:
cout<<" Enter airport code whose dis to be measured from LGA(nor):";
gets(acode);
dist=l1.srchnor(acode);
if(dist==-1)
{
cout<<" No such airport is present";
}
else
{
cout<<" Distance of "<<acode<<" from LGA is "<<dist;
}
break;
case 4:
l1.view();
break;
case 5:
l1.freemem();
break;
default:
cout<<" Wrong choice ";

}
cout<<" Do want to go back to main menu(y/n):";
cin>>ch;

}while(ch=='y'||ch=='Y');

l1.freemem();
return 0;
}

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