x-reaper
Reputation: 11
finding min value with sorted list in c++
I'm making a program with sorted list that has a variety of functions I'm supposed to build in the header source file. So far I have everything working perfectly but when I ask for the min value the first time it gives me the second highest value, 1, instead of the lowest which is 0. It gives me the lowest number the second time I ask, but I assume it's because it's not reaching the end of the linked list, but I'm not sure what to change.
Here's the header
#include <iostream>
using std::cout;
using std::endl;
#ifndef LINKEDLIST_H
#define LINKEDLIST_H
class LinkedList
{
private:
struct Node
{
int data;
Node *next;
};
int size;
Node *head, *tail;
public:
LinkedList();
~LinkedList();
// misc
void display();
// sorting and searching
// reverse --> sorting in descending
int linearSearch(int key);
void sort();
void reverse();
// various math
int min();
int max();
int mean();
// adding
void append(int num);
void insert(int num, int pos);
// removing
void pop();
void remove(int pos);
};
#endif // LINKEDLIST_H
source file
#include "linkedlist.h"
// GIVEN TO STUDENTS
LinkedList::LinkedList()
{
head = nullptr;
tail = nullptr;
size = 0;
}
LinkedList::~LinkedList()
{
if(head != nullptr)
{
Node *temp;
while(head != nullptr)
{
temp = head->next;
// deletes head
delete head;
// goes to next element
head = temp;
}
}
}
void LinkedList::display()
{
Node *temp = head;
for(int i = 0; i < size; i++)
{
cout << temp->data << "\t";
temp = temp->next;
}
cout << endl;
}
void LinkedList::append(int num)
{
// list is empty
if(head == nullptr)
{
head = new Node;
head->data = num;
head->next = nullptr;
// sets tail to head
tail = head;
}
else
{
// creates new node
Node *temp = new Node;
// sets new node data
temp->data = num;
temp->next = nullptr;
// sets previous tail link to new node
tail->next = temp;
// sets this node to new tail
tail = temp;
}
// increments size
size++;
}
void LinkedList::pop()
{
if(size > 1)
{
Node *temp = head;
// loops to node before tail
while(temp->next->next != nullptr)
{
temp = temp->next;
}
// deletes tail
delete tail;
// sets new tail
tail = temp;
tail->next = nullptr;
}
// if there's only one item
else if(size == 1)
{
Node *temp = tail;
// head and tail are now null
head = nullptr;
tail = nullptr;
// deletes node
delete temp;
}
size--;
}
// END GIVEN TO STUDENTS
void LinkedList::insert(int num, int pos)
{
if(pos ==0)
{
Node *temp=new Node;
temp->data=num;
temp->next=head;
head=temp;
}
if(pos>1)
{
Node *pre=new Node;
Node *cur=new Node;
Node *temp=new Node;
cur=head;
for(int i=1;i<pos+1;i++)
{
pre=cur;
cur=cur->next;
}
temp->data=num;
pre->next=temp;
temp->next=cur;
}
size++;
}
int LinkedList::linearSearch(int key)
{
Node *temp = head;
for(int i = 0; i < size; i++)
{
if(temp->data == key)
{
return i;
}
temp = temp->next;
}
return -1;
}
void LinkedList::reverse()
{
Node* temp = head;
// Traverse the List
while (temp)
{
Node* min = temp;
Node* r = temp->next;
// Traverse the unsorted sublist
while (r)
{
if (min->data < r->data)
min = r;
r = r->next;
}
// Swap Data
int x = temp->data;
temp->data = min->data;
min->data = x;
temp = temp->next;
}
}
void LinkedList::remove(int pos)
{
Node *temp = head;
if(pos ==0)
{
head = temp->next;
free(temp);
}
if(pos>1)
{
Node *current=new Node;
Node *previous=new Node;
current=head;
for(int i=1;i<pos+1;i++)
{
previous=current;
current=current->next;
}
previous->next=current->next;
}
size--;
}
void LinkedList::sort()
{
Node* temp = head;
// Traverse the List
while (temp) {
Node* min = temp;
Node* r = temp->next;
// Traverse the unsorted sublist
while (r) {
if (min->data > r->data)
min = r;
r = r->next;
}
// Swap Data
int x = temp->data;
temp->data = min->data;
min->data = x;
temp = temp->next;
}
}
int LinkedList::min()
{
int min = INT_MAX;
for(Node* temp = head; temp != nullptr; temp = temp->next)
{
if (head->data < min)
{
min = temp->data;
}
}
return min;
}
int LinkedList::max()
{
int max = INT_MIN;
for (Node* temp = head; temp != nullptr; temp = temp->next)
{
if (temp->data > max)
{
max = temp->data;
}
}
return max;
}
int LinkedList::mean()
{
if (!head)
return -1;
int count = 0; // Initialize count
int sum = 0;
float avg = 0.0;
struct Node* current = head; // Initialize current
while (current != NULL) {
count++;
sum += current->data;
current = current->next;
}
// calculate average
avg = (double)sum / count;
return avg;
}
and main
#include <iostream>
#include "linkedlist.h"
using namespace std;
int main()
{
LinkedList nums;
// adding through append
nums.append(8);
nums.append(6);
nums.append(7);
nums.append(8);
nums.append(0);
nums.append(9);
// displays list
cout << "List after append: " << endl;
nums.display();
cout << endl;
// adding through insert
nums.insert(1, 0);
nums.insert(5, 4);
nums.insert(3, 7);
// displays list
cout << "List after inserting: " << endl;
nums.display();
cout << endl;
// testing searching
cout << "Testing linear search:" << endl;
int pres = nums.linearSearch(7);
if(pres < 0)
{
cout << "7 is not present in the list." << endl;
}
else
{
cout << "7 can be found at location " << pres << endl;
}
pres = nums.linearSearch(5);
if(pres < 0)
{
cout << "5 is not present in the list." << endl;
}
else
{
cout << "5 can be found at location " << pres << endl;
}
cout << endl;
// does math
cout << "Minimum, maximum, and average before removing any items: " << endl;
cout << "Min: " << nums.min() << endl;
cout << "Max: " << nums.max() << endl;
cout << "Mean: " << nums.mean() << endl << endl;
// displays items reversed
cout << "Items reversed: " << endl;
nums.reverse();
nums.display();
cout << endl;
// removing through pop
nums.pop();
nums.pop();
// displays list
cout << "List after popping: " << endl;
nums.display();
cout << endl;
// removing through remove
nums.remove(0);
nums.remove(2);
nums.remove(4);
// displays list
cout << "List after removing: " << endl;
nums.display();
cout << endl;
// displays items sorted
cout << "Items sorted: " << endl;
nums.sort();
nums.display();
cout << endl;
// does math
cout << "Minimum, maximum, and average after removing items: " << endl;
cout << "Min: " << nums.min() << endl;
cout << "Max: " << nums.max() << endl;
cout << "Mean: " << nums.mean() << endl << endl;
// testing searching
cout << "Testing linear search:" << endl;
pres = nums.linearSearch(7);
if(pres < 0)
{
cout << "7 is not present in the list." << endl;
}
else
{
cout << "7 can be found at location " << pres << endl;
}
pres = nums.linearSearch(5);
if(pres < 0)
{
cout << "5 is not present in the list." << endl;
}
else
{
cout << "5 can be found at location " << pres << endl;
}
return 0;
}
Upvotes: 0
Views: 304
Answers (1)
Brandon Moretz
Reputation: 7621
I think you have a typo in your min function, it always compares head-data to the min instead of the temp node. Try this:
int LinkedList::min()
{
int min = INT_MAX;
for(Node* temp = head; temp != nullptr; temp = temp->next)
{
min = temp->data < min ? temp->data : min;
}
return min;
}
Upvotes: 2
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