Problem 4

#include <iostream>
#include <cstdio>
#include <ctype.h>
using namespace std;
struct counting{

    int count;
    int data;

    struct counting *next;

};

typedef counting node;

node  *charterInsert(node *head){

        node *temp, *prev ,*temp2;

        for(int i = 'a'; i<='z'; i++){


        if(head == NULL){
            head = new node();
            temp = new node();

            temp->data = i;
            temp->count=0;
            temp->next = NULL;
            head->next = temp;
            prev = temp;

    }
    else{

        temp2 = new node();
        temp2->data =i;
        temp2->count=0;
        temp2->next = NULL;
        prev->next = temp2;

        prev = temp2;


    }



}

  return head;

}

node *charCount(node *head){


        string str;
        int len;
        node *temp;

        cin>>str;
        len = str.size();

    for(int i=0; i<len; i++){

        //printf("%c",str[i]);

        temp =head->next;

        while(temp !=NULL){

            //printf(" %c ",temp->data);
            if(tolower(str[i]) == temp->data){
            temp->count++;
        }
            temp= temp->next;
        }


    }


return head;
}




void display(node *head){
    head=head->next;

    while(head!=NULL){


        printf("%c = %d\n",head->data, head->count);

        head = head->next;
    }

}


int main()
{

   node *head;

   head = NULL;


  head =  charterInsert(head);

    head = charCount(head);


  display(head);

    return 0;
}