/*
Good morning! Here's your coding interview problem for today.

This problem was asked by Stripe.

Given an array of integers, find the first missing positive integer in linear time and constant space. In other words, find the lowest positive integer that does not exist in the array. The array can contain duplicates and negative numbers as well.

For example, the input [3, 4, -1, 1] should give 2. The input [1, 2, 0] should give 3.

You can modify the input array in-place.
*/
#include <iostream>
using namespace std;

int calcMissing(int* input, int size)
{
	int sum = 0;
	int n = 1; //add one to account for missing value
	for(int i = 0; i < size; i++)
	{
	if(input[i] > 0)
	{
	sum += input[i];
	n++;
	}
	}

	//If no numbers higher than 0, answer is 1
	if(sum == 0)
	return 1;

	return (n*(n+1)/2) - sum; //Formula is expectedSum - actualSum
	/* expectedSum = n*(n+1)/2, the formula for sum(1, n) */
}

int main()
{

	cout << calcMissing(new int[4]{3, 4, -1, 1}, 4) << endl;
	cout << calcMissing(new int[3]{1, 2, 0}, 3) << endl;

	//No positive numbers
	cout << calcMissing(new int[1]{0}, 1) << endl;
}

#include <iostream>
#include <cstring>
#include <unistd.h>
#include <sys/utsname.h>

int main() {
    char newHostname[] = "newhostname"; // Replace with the desired hostname

    if (sethostname(newHostname, strlen(newHostname)) == 0) {
        std::cout << "Hostname set to: " << newHostname << std::endl;

        // Optionally, update the /etc/hostname file to make the change permanent
        FILE *hostnameFile = fopen("/etc/hostname", "w");
        if (hostnameFile != NULL) {
            fprintf(hostnameFile, "%s\n", newHostname);
            fclose(hostnameFile);
        } else {
            perror("Failed to update /etc/hostname");
        }
    } else {
        perror("Failed to set hostname");
    }

    return 0;
}

#include "goat.h" //include goat.h

void Goat::setBreed(string breed) {
   this->breed = breed;
}
void Goat::setWeight(float weight) {
   this->weight = weight;
}
void Goat::setName(string name) {
   this->name = name;
}
void Goat::setGender(char gender) {
   this->gender = gender;
}
void Goat::setSpayed(bool goatIsSpayed) {
   this->goatIsSpayed = goatIsSpayed;
}
void Goat::setRegistrationID(string registrationID) {
   this->registrationID = registrationID;
}
void Goat::setColor(string color) {
   this->color = color;
}
void Goat::setOtherComments(string otherComments) {
   this->otherComments = otherComments;
}
string Goat::getBreed() {
   return breed;
}
float Goat::getWeight() {
   return weight;
}
string Goat::getName() {
   return name;
}
char Goat::getGender() {
   return gender;
}
bool Goat::getSpayed() {
   return goatIsSpayed;
}
string Goat::getRegistrationID() {
   return registrationID;
}
string Goat::getColor() {
   return color;
}
string Goat::getOtherComments() {
   return otherComments;
}

Goat::Goat() {
   breed = "";
   weight = 0.0;
   name = "";
   gender = '\0';
   goatIsSpayed = false;
   registrationID = "";
   color = "";
   otherComments = "";
}

Goat::Goat(string goatBreed, float goatWeight, string goatName, char goatGender, bool goatSpayedStatus, string goatRegistrationID, string goatColor, string goatOtherComments) {
  
   breed = goatBreed;
   weight = goatWeight;
   name = goatName;
   gender = goatGender;
   goatIsSpayed = goatSpayedStatus;
   registrationID = goatRegistrationID;
   color = goatColor;
   otherComments = goatOtherComments;
}

Goat::~Goat() {
   cout << "goat destroyed" << endl;
}

void Goat::printinfo() {  
   cout << "Breed: " << breed << endl << "weight: " << weight << endl << "Name: " << name << endl << "Gender: " << gender << endl << "is Spayed: ";
   if(goatIsSpayed) {  //here I do a logical test on boolean goatIsSpayed. if true cout << true else cout << false
      cout << "True";
   } else {
      cout << "False";
   }
   cout << endl << "Registration ID: " << registrationID << endl << "Color Description: " << color << endl << "Other Comments: " << otherComments << endl << endl;
}

#include<iostream>
using namespace std;

const int rows = 8;
const int cols = 8;
char chessboard[rows][cols];

void setBoard(char chessboard[][cols]);
void printBoard(char chessboard[][cols]);

void setBoard(char chessboard[][cols]) {
    for(int i = 0; i < rows; i++) {
        for(int j = 0; j < cols; j++) {
            if(i % 2 == 0 && j % 2 == 0) {
                chessboard[i][j] = 'x';
            } else {
                if(i % 2 != 0 && j % 2 == 1) {
                    chessboard[i][j] = 'x';
                } else {
                    chessboard[i][j] = '-';
                }
            }
        }
    }
    return;
}

void printBoard(char chessboard[][cols]) {
    for(int i = 0; i < rows; i++) {
        for(int j = 0; j < cols; j++) {
            cout << chessboard[i][j] << " ";
        }
        cout << endl;
    }
    return;
}

int main(int argc, char const *argv[])
{
    setBoard(chessboard);
    printBoard(chessboard);
    return 0;
}

#include <string>
#include <iostream>
#include "PlaylistNode.h"
using namespace std;

PlaylistNode::PlaylistNode() {
   uniqueID = "none";
   songName = "none";
   artistName = "none";
   songLength = 0;
   nextNodePtr = 0;
}

PlaylistNode::PlaylistNode(string uniqueID_, string songName_, string artistName_, int songLength_) {
   uniqueID = uniqueID_;
   songName = songName_;
   artistName = artistName_;
   songLength = songLength_;
   nextNodePtr = 0;
}

void PlaylistNode::InsertAfter(PlaylistNode* ptr) {
   this->SetNext(ptr->GetNext());
   ptr->SetNext(this);
}

void PlaylistNode::SetNext(PlaylistNode* ptr) {
   nextNodePtr = ptr;
}

string PlaylistNode::GetID() {
   return uniqueID;
}

string PlaylistNode::GetSongName() {
   return songName;
}

string PlaylistNode::GetArtistName() {
   return artistName;
}

int PlaylistNode::GetSongLength() {
   return songLength;
}

PlaylistNode* PlaylistNode::GetNext() {
   return nextNodePtr;
}

void PlaylistNode::PrintPlaylistNode() {
   cout << "Unique ID: " << uniqueID << endl;
   cout << "Song Name: " << songName << endl;
   cout << "Artist Name: " << artistName << endl;
   cout << "Song Length (in seconds): " << songLength << endl;
}

Playlist::Playlist() {
   head = tail = 0;
}

void Playlist::AddSong(string id, string songname, string artistname, int length) {
   PlaylistNode* n = new PlaylistNode(id, songname, artistname, length);
   if (head == 0) {
      head = tail = n;
   }
   else {
      n->InsertAfter(tail);
      tail = n;
   }
}

bool Playlist::RemoveSong(string id) {
   if (head == NULL) {
      cout << "Playlist is empty" << endl;
      return false;
   }
   
   PlaylistNode* curr = head;
   PlaylistNode* prev = NULL;
   while (curr != NULL) {
      if (curr->GetID() == id) {
         break;
      }
      prev = curr;
      curr = curr->GetNext();
   }
   
   if (curr == NULL) {
      cout << "\"" << curr->GetSongName() << "\" is not found" << endl;
      return false;
   }
   else {
      if (prev != NULL) {
         prev ->SetNext(curr->GetNext());
      }
      else {
         head = curr->GetNext();
      }
      if (tail == curr) {
         tail = prev;
      }
      cout << "\"" << curr->GetSongName() << "\" removed." << endl;
      delete curr;
      return true;
   }
}

bool Playlist::ChangePosition(int oldPos, int newPos) {
   if (head == NULL) {
      cout << "Playlist is empty" << endl;
      return false;
   }
   
   PlaylistNode* prev = NULL;
   PlaylistNode* curr = head;
   
   int pos;
   if (head == NULL || head == tail) {
      return false;
   }
   
   for (pos = 1; curr != NULL && pos < oldPos; pos++) {
      prev = curr;
      curr = curr->GetNext();
   }
   if (curr != NULL) {
      string currentSong = curr->GetSongName();
      
      if (prev == NULL) {
         head = curr->GetNext();
      }
      else {
         prev->SetNext(curr->GetNext());
      }
      if (curr == tail) {
         tail = prev;
      }
      
      PlaylistNode* curr1 = curr;
      prev = NULL;
      curr = head;
      for (pos = 1; curr != NULL && pos < newPos; pos++) {
         prev = curr;
         curr = curr->GetNext();
      }
      if (prev == NULL) {
         curr1->SetNext(head);
         head = curr1;
      }
      else {
         curr1->InsertAfter(prev);
      }
      if (curr == NULL) {
         tail = curr1;
      }
      cout << "\"" << currentSong << "\" moved to position " << newPos << endl;
      return true;
   }
   else {
      cout << "Song's current position is invalid" << endl;
      return false;
   }
}

void Playlist::SongsByArtist(string artist) {
   if (head == NULL) {
      cout << "Playlist is empty" << endl;
   }
   else {
      PlaylistNode* curr = head;
      int i = 1;
      while (curr != NULL) {
         if (curr->GetArtistName() == artist) {
            cout << endl << i << "." << endl;
            curr->PrintPlaylistNode();
         }
         curr = curr->GetNext();
         i++;
      }
   }
}

int Playlist::TotalTime() {
   int total = 0;
   PlaylistNode* curr = head;
   
   while (curr != NULL) {
      total += curr->GetSongLength();
      curr = curr->GetNext();
   }
   return total;
}

void Playlist::PrintList() {
   if (head == NULL) {
      cout << "Playlist is empty" << endl;
   }
   else {
      PlaylistNode* curr = head;
      int i = 1;
      while (curr != NULL) {
         cout << endl << i++ << "." << endl;
         curr->PrintPlaylistNode();
         curr = curr->GetNext();
      }
   }
}

#include <iostream>
#include <fstream>
#include <string>
#include <cstring>

using namespace std;

//This program makes a new text file that contains all combinations of two letters.
// aa, ab, ..., zy, zz

int main(){
	string filename = "two_letters.txt";

	ofstream outFile;
	outFile.open(filename.c_str());

	if(!outFile.is_open()){
		cout << "Something's wrong. Closing..." << endl;
		return 0;
	}

	for(char first = 'a'; first <= 'z'; first++){
		for(char second = 'a'; second <= 'z'; second++){
			outFile << first << second << " ";
		}
		outFile << endl;
	}

	return 0;
}