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C++ Linked List Exercises: Find middle element in a single linked list

C++ Linked List: Exercise-6 with Solution

Write a C++ program to find the middle element of a given Linked List.

Test Data:
Original list:
9 7 5 3 1
Middle element of the said list:
5
Original list:
7 5 3 1
Middle element of the said list:
3
Explanation: The second node of the list is returned since it has the values 5 and 3.

Sample Solution:

C++ Code:

#include <iostream>

using namespace std;

struct  Node
{   
    int num;
    Node *next;
 }; //node constructed

  int size = 0;
  void insert(Node** head, int num){
    Node* new_Node = new Node();
    new_Node->num = num;
    new_Node->next = *head;
    *head = new_Node;    
     size++;
}


int get_Middle(Node *head)
{
    if(!head) return -1;
    int c = 0;
    Node *middle = head;
    while( head ) {
        if(c%2 != 0) middle = middle->next;
        c++;
        head = head->next;
    }
    return middle->num;
}

  //Display all nodes
  void display_all_nodes(Node* node)
    { 
      while(node!=NULL){
        cout << node->num << " "; 
        node = node->next; 
    } 
}

int main()
{
    Node* head = NULL;

    insert(&head,1);
    insert(&head,3);
   insert(&head,5);
   insert(&head,7);
    cout << "Original list:\n";
    display_all_nodes(head); 
    cout << "\nMiddle element of the said list:";
    cout << "\n" << get_Middle(head) << "\n";
    cout << "\nOriginal list:\n";
    insert(&head,9);
    display_all_nodes(head); 
    cout << "\nMiddle element of the said list:";
    cout << "\n" << get_Middle(head);
    cout<<endl;
    return 0;
}

Sample Output:

Original list:
7 5 3 1
Middle element of the said list:
3

Original list:
9 7 5 3 1
Middle element of the said list:
5

Flowchart:

Flowchart: Find middle element in a single linked list.
Flowchart: Find middle element in a single linked list.

CPP Code Editor:

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Previous C++ Exercise: Insert a new node at the end of a Linked List.
Next C++ Exercise: Insert new node at the middle of a Singly Linked List.

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C++ Programming: Tips of the Day

How to replace all occurrences of a character in string?

std::string doesn't contain such function but you could use stand-alone replace function from algorithm header.

#include <algorithm>
#include <string>

void some_func() {
  std::string s = "example string";
  std::replace( s.begin(), s.end(), 'x', 'y'); // replace all 'x' to 'y'
}

Ref: https://bit.ly/3niU71x