#include <iostream>
using namespace std;

int main() {

cout << "Hello World!\n";
// Prints out "Hello World"
return 0;

}

/*
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 <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;
}

/*
this program will simulate the spreading of a disease through a 
grid of people, starting from a user-defined person. It will count
the number of turns taken before everyone on the grid is immunized
to the disease after having caught it once.
This program will user the SIR model (Susceptible, Infectious, Recovered)
 and cellular automata to simulate the people in the grid.
*/
#include <iostream>
using namespace std;

/* Any and all global variables */
const int SIZE = 8; //Size of the square person array

/* Any and all functions */
void gridDefaultify(char[][SIZE], int);
	//Purpose: Sets each item in the person array to 's'
	//Parameters: A square, two-dimensional array
	//            The size of that array's bounds
void gridDisplay(char[][SIZE], int);
	//Purpose: Formats and prints the information in the person grid
	//Parameters: A square, two-dimensional array
	//            The value of the current day
void nextTurn(char[][SIZE], char[][SIZE], int&);
	//Purpose: Updates the grid of people, and the current day
	//Parameters: Two square, two-dimensional arrays
	//            A reference to the current day (so that it can be updated)
int countInfected(char[][SIZE], int);
	//Purpose: Counts the number of infectious people on the grid
	//Parameters: A square, two-dimensional array
	//            The size of that array's bounds


int main(){
	int currentDay = 0; //Infection begins on day 0, and ends one day after the last person is Recovered
	char gridCurrent[SIZE][SIZE]; //Grid of all people
	char gridUpdate[SIZE][SIZE]; //Where the user chooses to start the infection
	int xToInfect;
	int yToInfect; //Set of coordinates for the initial infection position, given by user
	
	//Initializes the grids to all 's'
	gridDefaultify(gridCurrent, SIZE);
	gridDefaultify(gridUpdate, SIZE);
	
	//The below block gets the initial infection coordinates from the user
	cout << "Please enter a location to infect: ";
	while(true){
		cin >> xToInfect >> yToInfect;

		xToInfect--;
		yToInfect--;
		
		if(xToInfect < 0 || yToInfect < 0 || xToInfect >= SIZE || yToInfect >= SIZE){
			cout << "Those coordinates are outside the bounds of this region." << endl;
			cout << "Please enter another location to infect: ";
			continue;
		} else {
			gridCurrent[xToInfect][yToInfect] = 'i';
			break;
		}
	}
	
	//Displays the initial state of the grid
	gridDisplay(gridCurrent, currentDay);
	
	//The below block will display and update the grid until the infection is done.
	while(true){
		nextTurn(gridCurrent, gridUpdate, currentDay);
		gridDisplay(gridCurrent, currentDay);
		if(countInfected(gridCurrent, SIZE) == 0) break; //Once there are no more infected, the game is done
	}
	
	//Displays the number of days taken for the infection to end
	cout << "It took " << currentDay + 1 << " days for the outbreak to end";
	
	cout << endl;
	return 0;
}

void gridDefaultify(char arr[][SIZE], int arrSize){
	for(int x = 0; x < arrSize; x++){
		for(int y = 0; y < arrSize; y++){
			arr[x][y] = 's'; //Sets all items in the passed-in array to 's'
		}
	}
	return;
}

void gridDisplay(char arr[][SIZE], int day){
	cout << "Day " << day << endl; //Prints the current day
	for(int x = 0; x < SIZE; x++){
		for(int y = 0; y < SIZE; y++){
			cout << arr[x][y] <<" "; //Prints the array's contents
		}
		cout << endl; //Formats with newlines
	}
	cout << endl; //Some spacing
	return;
}

void nextTurn(char today[][SIZE], char update[][SIZE], int& day){
	day++; //Updates the day
	int xCheck; //X coordinate to be checked
	int yCheck; //Y coordinate to be checked
	
	for(int x = 0; x < SIZE; x++){
		for(int y = 0; y < SIZE; y++){
			//Sets all 'i' to 'r' in the new grid
			if(today[x][y] == 'i' || today[x][y] == 'r'){
				update[x][y] = 'r'; //Updates all infectious to recovered, and keeps current recovered
			}
			if(today[x][y] == 's'){									// If the person is susceptible...
				for(int xCheck = x-1; xCheck <= x+1; xCheck++){		// Check all x coordinates around the person
					for(int yCheck = y-1; yCheck <= y+1; yCheck++){	// Check all y coordinates around the person
						if(xCheck == x && yCheck == y){
																	// Don't check at the person because there is no need to check there
						} else {
							if(xCheck >= 0 && yCheck >= 0 && xCheck < SIZE && yCheck < SIZE){ // Make sure the checked coordinates are in bounds
								if(today[xCheck][yCheck] == 'i'){	//Is the person at the checked coordinates infected?
									update[x][y] = 'i';				//If so, update the 's' to 'i' in the new grid
								}
							}
						}
					}
				}
			}
		}
	}
	
	for(int x = 0; x < SIZE; x++){
		for(int y = 0; y < SIZE; y++){
			today[x][y] = update[x][y]; //Updates today's grid with the new values
		}
	}
}

int countInfected(char arr[][SIZE], int arrSize){
	int count = 0;
	
	for(int x = 0; x < arrSize; x++){
		for(int y = 0; y < arrSize; y++){
			if(arr[x][y] == 'i') count++; //Increments count for each infected person in the grid
		}
	}
	
	return count;
}

//Leif Messinger
//Finds all sets of 5 5 letter words that don't have duplicate letters in either themselves or each other.
//First it reads the words in and puts them in groups of their bitmasks
//After that, we recurse on each group. Before doing that, we remove the group from the set of other groups to check it against.
#include <cstdio> //getchar, printf
#include <cassert> //assert
#include <vector>
#include <set>
#include <algorithm> //std::copy_if
#include <iterator> //std::back_inserter

#define CHECK_FOR_CRLF true
#define MIN_WORDS 5
#define MAX_WORDS 5
#define WORD_TOO_LONG(len) (len != 5)

const unsigned int charToBitmask(const char bruh){
	assert(bruh >= 'a' && bruh <= 'z');
	return (1 << (bruh - 'a'));
}

void printBitmask(unsigned int bitmask){
	char start = 'a';
	while(bitmask != 0){
		if(bitmask & 1){
			putchar(start);
		}

		bitmask >>= 1;
		++start;
	}
}

//Pointer needs to be deleted
const std::set<unsigned int>* getBitmasks(){
	std::set<unsigned int>* bitmasksPointer = new std::set<unsigned int>;
	std::set<unsigned int>& bitmasks = (*bitmasksPointer);

	unsigned int bitmask = 0;
	unsigned int wordLength = 0;
	bool duplicateLetters = false;
	for(char c = getchar(); c >= 0; c = getchar()){
		if(CHECK_FOR_CRLF && c == '\r'){
			continue;
		}
		if(c == '\n'){
			if(!(WORD_TOO_LONG(wordLength) || duplicateLetters)) bitmasks.insert(bitmask);
			bitmask = 0;
			wordLength = 0;
			duplicateLetters = false;
			continue;
		}
		if((bitmask & charToBitmask(c)) != 0) duplicateLetters = true;
		bitmask |= charToBitmask(c);
		++wordLength;
	}

	return bitmasksPointer;
}

void printBitmasks(const std::vector<unsigned int>& bitmasks){
	for(unsigned int bruh : bitmasks){
		printBitmask(bruh);
		putchar(','); putchar(' ');
	}
	puts("");
}

//Just to be clear, when I mean "word", I mean a group of words with the same letters.
void recurse(std::vector<unsigned int>& oldBitmasks, std::vector<unsigned int> history, const unsigned int currentBitmask){
	//If there's not enough words left
	if(oldBitmasks.size() + (-(history.size())) + (-MIN_WORDS) <= 0){
		//If there's enough words
		if(history.size() >= MIN_WORDS){
			//Print the list
			printBitmasks(history);
		}
		return;
	//To make it faster, we can stop it after 5 words too
	}else if(history.size() >= MAX_WORDS){
		//Print the list
		printBitmasks(history);
		return;
	}

	//Thin out the array with only stuff that matches the currentBitmask.
	std::vector<unsigned int> newBitmasks;
	std::copy_if(oldBitmasks.begin(), oldBitmasks.end(), std::back_inserter(newBitmasks), [&currentBitmask](unsigned int bruh){
		return (bruh & currentBitmask) == 0;
	});

	while(newBitmasks.size() > 0){
		//I know this modifies 'oldBitmasks' too. It's intentional.
		//This makes it so that the word is never involved in any of the child serches or any of the later searches in this while loop.
		const unsigned int word = newBitmasks.back(); newBitmasks.pop_back();

		std::vector<unsigned int> newHistory = history;
		newHistory.push_back(word);

		recurse(newBitmasks, newHistory, currentBitmask | word);
	}
}

int main(){
	const std::set<unsigned int>* bitmasksSet = getBitmasks();
	std::vector<unsigned int> bitmasks(bitmasksSet->begin(), bitmasksSet->end());
	delete bitmasksSet;

	recurse(bitmasks, std::vector<unsigned int>(), 0);

	return 0;
}

#define NUM_BITS 8

#include <iostream>


struct Number{
    int num : NUM_BITS;
    Number(){}
    Number(const int& bruh){
        num = bruh;
    }
    operator int() const { return num; }
    Number& operator=(const int& bruh){
        num = bruh;
        return (*this);
    }
};

using namespace std;

bool isNegative(const int& num){
    //This gets the bitwise and of num and 10000000000000000000000000000000
    //This implicit casts to bool, which means (num & (1 << 31)) != 0
    return (num & (1 << 31));
}

void printBinaryNumber(const int& num, const int numBits){
    for(int i = numBits; i > 0; --i){
        //8..1
        int bitMask = 1 << (i-1);
        if(num & bitMask){ //Test the bit
            cout << '1';
        }else{
            cout << '0';
        }
    }
}

void printCarryBits(const int& a, const int& b, const int numBits){
    int answer = 0;
    
    bool carry = false;
    for(int i = 0; i < numBits; ++i){
        //8..1
        int bitMask = 1 << i;
        bool aBit = a & bitMask;
        bool bBit = b & bitMask;
        if(aBit && bBit || aBit && carry || bBit && carry){ //Carry bit is true next
            if(carry)
                answer |= bitMask;
            carry = true;
        }else{
            if(carry)
                answer |= bitMask;
            carry = false;
        }
    }
    printBinaryNumber(answer, 8);
}


void printBorrowBits(const int& a, const int& b, const int numBits){
    int answer = 0;
    
    bool carry = false;
    for(int i = 0; i < numBits; ++i){
        //8..1
        int bitMask = 1 << i;
        bool aBit = a & bitMask;
        bool bBit = b & bitMask;
        if((!(aBit ^ carry)) && bBit){ //Carry bit is true next
            if(carry)
                answer |= bitMask;
            carry = true;
        }else{
            if(carry)
                answer |= bitMask;
            carry = false;
        }
    }
    printBinaryNumber(answer, 8);
}

void doProblem(const int& a, const int& b, const char& sign, const int& result, const int& numBits){
    if(sign == '+'){
        cout << ' '; printCarryBits(a, b, numBits); cout << endl;
    }else{
        cout << ' '; printBorrowBits(a, b, numBits); cout << endl;
    }
    cout << ' '; printBinaryNumber(a, numBits); cout << endl;
    cout << sign; printBinaryNumber(b, numBits); cout << endl;
    cout << "----------" << endl;
    cout << ""; printBinaryNumber(result, numBits + 1); cout << " = " << result;
    cout << endl;
}

int main(){
    
    Number a = 0b110;
    Number b = 0b011;
    cout<< a << endl << b << endl;
    
    doProblem(a, b, '+', a + b, NUM_BITS);
    doProblem(a, b, '-', a - b, NUM_BITS);
    doProblem(-a, b, '+', -a + b, NUM_BITS);
    doProblem(a, b, '-', -a - b, NUM_BITS);
    

    return 0;
}