path: root / Year 1 / Programming introduction / Homeworks / homework1.cpp

#include <iostream>
#include <cmath>
#include <stdlib.h> // rand and srand for ex. 5

using namespace std;

/*
 * Exercise 0
 */

/* Floating point arithmetic */

double const FLOAT_EPSILON_FLOOR = 0.0001, FLOAT_EPSILON_CEIL = FLOAT_EPSILON_FLOOR * 9;

bool eq(double a, double b)
{
	return ((a - b) < 0.0 ? (b - a) : (a - b)) <= FLOAT_EPSILON_FLOOR;
}

bool lt(double a, double b)
{
	return !eq(a, b) && (a - b) < FLOAT_EPSILON_CEIL;
}

bool mt(double a, double b)
{
	return lt(b, a);
}

/* Planimetry */

double distanceBetweenPoints(int x1, int y1, int x2, int y2)
{
	int sideA = x1 - x2, sideB = y1 - y2;
	return sqrt(sideA * sideA + sideB * sideB); // Pythagorean theorem
}

/* Exercise calculations */

void ex0()
{
	// These should be precalculated, but this shows how they're found out
	// The coordinates of points B, C, D and E are some combination of positive and/or negative values of 2.828
	float const CROSS_PNT = 2.828,
				SLOPE_B =  CROSS_PNT /  CROSS_PNT,
				SLOPE_C = -CROSS_PNT / -CROSS_PNT,
				SLOPE_D = -CROSS_PNT /  CROSS_PNT,
				SLOPE_E =  CROSS_PNT / -CROSS_PNT;

	double x, y;
	cin >> x >> y;

	if (eq(x, 0)) // if it's on the Y ordinate
	{
		cout << "On a line" << endl;
	}
	else if (lt(distanceBetweenPoints(0, 0, x, y), 4.0))
	{
		double pointSlope = y / x;

		if (eq(x, -CROSS_PNT) || eq(x, CROSS_PNT)
			|| eq(pointSlope, SLOPE_B) || eq(pointSlope, SLOPE_C) || eq(pointSlope, SLOPE_D) || eq(pointSlope, SLOPE_E))
		{
			cout << "On a line" << endl;
		}
		else if ((mt(y, 0) || eq(y, 0)) && mt(x, 0)) // Check 1st quadrant
		{
			if (mt(pointSlope, SLOPE_B))
				cout << "Inside green area!" << endl;
			else if (mt(x, CROSS_PNT))
				cout << "Inside purple area!" << endl;
			else
				cout << "Inside yellow area!" << endl;
		}
		else if ((mt(y, 0) || eq(y, 0)) && lt(x, 0)) // Check 2nd quadrant
		{
			if (lt(pointSlope, SLOPE_D))
				cout << "Inside red area!" << endl;
			else if (x > -CROSS_PNT)
				cout << "Inside pink area!" << endl;
		}
		else if (lt(y, 0) && lt(x, 0)) // Check 3rd quadrant
		{
			if (mt(pointSlope, SLOPE_C))
				cout << "Inside blue area!" << endl;
			else if (mt(x, -CROSS_PNT))
				cout << "Inside pink area!" << endl;
		}
		else // Check 4th quadrant
		{
			if (mt(pointSlope, SLOPE_E) && mt(x, CROSS_PNT))
				cout << "Inside purple area!" << endl;
			else
				cout << "Inside yellow area!" << endl;
		}
	}
	else if ((lt(-2, x) && lt(x, 2)) && (lt(-6, y) && lt(y, -7))) // Outside circle and in rectangle
	{
		cout << "Inside grey area" << endl;
	}
}

/*
 * Exercise 1
 */

double f(unsigned int k, int x)
{
	double sum = x;

	for (unsigned int i = 2; i <= k; i++)
	{
		if (i & 1)
			sum = 3 * sum + 1;
		else
			sum /= 2;
	}

	return sum;
}

void ex1()
{
	int x;
	cin >> x;

	cout << f(35, x) << endl;
}

/*
 * Exercise 2
 */

void setMarmaladeType(int type, int *blueberryMarmalades, int *peachMarmalades, int *rosehipMarmalades)
{
	if      (type %  7 == 0) *blueberryMarmalades += 1;
	else if (type % 13 == 0) *peachMarmalades     += 1;
	else if (type % 17 == 0) *rosehipMarmalades   += 1;
}

void ex2()
{
	int archiveLength;
	cin >> archiveLength;

	int blueberryMarmalades = 0, peachMarmalades = 0, rosehipMarmalades = 0;

	for (int i = 0, digit, countryDigits, typeDigits, type; i < archiveLength; i++)
	{
		cin >> digit;

		if (i % 8 == 0) // Reset at start of ID number
		{
			countryDigits = 1;
			typeDigits = type = 0;
		}
		else if (countryDigits < 3)
		{
			countryDigits++;
		}
		else if (typeDigits < 4)
		{
			typeDigits++;
			(type *= 10) += digit;
		}
		else if (typeDigits == 4)
		{
			setMarmaladeType(type, &blueberryMarmalades, &peachMarmalades, &rosehipMarmalades);
		}
	}

	cout << "Мармалад от боровинки: " << blueberryMarmalades << endl;
	cout << "Мармалад от праскови: " << peachMarmalades << endl;
	cout << "Шипков мармалад: " << rosehipMarmalades << endl;
}

/*
 * Exercise 4
 */

bool isInteresting(int n)
{
	int lastDigit;

	do
	{
		lastDigit = n % 10;
		n /= 10;

		if ((lastDigit & 1) == ((n % 10) & 1))
			return false;
	}
	while (n != 0);

	return true;
}

int sumOfInterestingNumsBetween(int a, int b)
{
	int sum = 0;

	for (int i = a; i <= b; i++)
	{
		if (isInteresting(i))
			sum += i;
	}

	return sum;
}

void ex4()
{
	int a, b;
	cin >> a >> b;

	cout << sumOfInterestingNumsBetween(a, b) << endl;
}

/* 
 * Exercise 5
 */

const int NUMBER_LENGTH = 4, N = 10;

int genSecretNum()
{
	// Initializes random seed (required for getting a random number on every program launch)
	// Taken from included reference: https://www.cplusplus.com/reference/cstdlib/rand#example
	srand (time(NULL));

	int rnd = rand(), result = 0;

	for (int i = 0; i < NUMBER_LENGTH;)
	{
		if (rnd % 10 != 0)
		{
			(result *= 10) += rnd % 10;
			i++;
		}
		else if (rnd == 0)
		{
			rnd = rand();
		}

		rnd /= 10;
	}

	return result;
}

bool digitInsideNum(int digit, int num)
{
	while (num != 0)
	{
		if (digit == num % 10)
			return true;

		num /= 10;
	}

	return false;
}

void countBullsAndCows(int secretNum, int guess, int *bulls, int *cows)
{
	*bulls = *cows = 0;
	
	 // If our secret num can contain zeroes, this (and the corresponding checks) should be changed to some other digit
	int secretCows = 0, guessCows = 0; 

	for (int i = 0; i < NUMBER_LENGTH; i++)
	{
		if (guess % 10 == secretNum % 10)
		{
			*bulls += 1;
		}
		else
		{
			(secretCows *= 10) += secretNum % 10;

			// Getting unique cows prevents the later cow loop from incrementing cows
			// multiple times when we have duplicate digits in secretNum and in guessCows
			if (!digitInsideNum(guess % 10, guessCows))
				(guessCows *= 10) += guess % 10;
		}

		secretNum /= 10;
		guess /= 10;
	}

	while (secretCows != 0)
	{
		if (digitInsideNum(secretCows % 10, guessCows))
			*cows += 1;

		secretCows /= 10;
	}
}

void playBullsAndCows()
{
	int secNum = genSecretNum(), guess = 0, bulls = 0, cows = 0;

	for (int i = 0; i < N; i++)
	{
		cin >> guess;

		if (guess == secNum)
		{
			cout << "Позна!" << endl;
			return;
		}
		else
		{
			countBullsAndCows(secNum, guess, &bulls, &cows);
			cout << bulls << " бикове и " << cows << " крави" << endl;
		}
	}

	cout << "Не позна в определения брой ходове!" << endl;
}

void ex5()
{
	playBullsAndCows();
}

int main()
{
	ex0();
}