//myClasses/Algorithms.hpp
//Matthew Ellison
// Created: 11-8-18
//Modified: 12-10-18
//This file contains the declarations and implementations to several algoritms that I have found useful
/*
	Copyright (C) 2018  Matthew Ellison

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

#ifndef MEE_ALGORITHMS_HPP
#define MEE_ALGORITHMS_HPP

#include <vector>
#include <cinttypes>
#include <algorithm>
#include <string>
//This library is licensed under lgplv3
//You can find more information at gmplib.org
#include <gmpxx.h>	//This is necessary for the getGmpFib function for numbers larger than a normal int can hold. It can be commented out if needed

namespace mee{


//A list of functions in the file
//Also works as prototypes with general information
//This is a function that returns all the primes <= goalNumber and returns a vector with those prime numbers
template<class T>
std::vector<T> getPrimes(T goalNumber);
//This is a function that gets all the divisors of num and returns a vector containing the divisors
template<class T>
std::vector<T> getDivisors(T num);
//This is a function that gets the sum of all elements in a vector and returns the number
template <class T>
T getSum(std::vector<T> numbers);
//This is a function that searches a vecter for an element. Returns true if num is found in list
template<class T>
bool isFound(T num, std::vector<T> list);
//This is a function that creates all permutations of a string and returns a vector of those permutations.
//It is meant to have only the string passed into it from the calling function. num is used for recursion purposes
//It can however be used with num if you want the first num characters to be stationary
std::vector<std::string> getPermutations(std::string master, int num = 0);
//These functions return the numth Fibonacci number
uint64_t getFib(uint64_t num);
void getFib(mpz_t fibNum, uint64_t num);
//This is a function that performs a bubble sort on a vector
template<class T>
bool bubbleSort(std::vector<T> nums);
//This is a function that perfomrs a quick sort on a vector
template<class T>
bool quickSort(std::vector<T> nums);
//This is a function that performs a search on a vector and returns the subscript of the item being searched for (-1 if not found)
template<class T>
int64_t search(std::vector<T> nums, T num);
//This function finds the smallest element in a vector
template<class T>
T findMin(std::vector<T> arr);
//This function finds the largest element in a vector
template<class T>
T findMax(std::vector<T> arr);


template<class T>
std::vector<T> getPrimes(T goalNumber){
	std::vector<T> primes;
	bool foundFactor = false;

	//If the number is 0 or a negative number return an empty vector
	if(goalNumber < 1){
		return primes;
	}

	//If the number is even 2 is a factor
	if((goalNumber % 2) == 0){
		primes.push_back(2);
	}
	//We can now start at 3 and skip all of the even numbers
	for(T possiblePrime = 3;possiblePrime <= goalNumber;possiblePrime += 2){
		//Step through every element in the current primes. If you don't find anything that divides it, it must be a prime itself
		for(uint64_t cnt = 0;(cnt < primes.size()) && ((primes.at(cnt) * primes.at(cnt)) < goalNumber);++cnt){
			if((possiblePrime % primes.at(cnt)) == 0){
				foundFactor = true;
				break;
			}
		}
		//If you didn't find a factor then it must be prime
		if(!foundFactor){
			primes.push_back(possiblePrime);
		}
		//If you did find a factor you need to reset the flag
		else{
			foundFactor = false;
		}
	}
	std::sort(primes.begin(), primes.end());
	return primes;
}

template<class T>
std::vector<T> getDivisors(T num){
	std::vector<T> divisors;	//Holds the number of divisors
	//You only need to go to sqrt(number). cnt * cnt is faster than sqrt()
	for(uint64_t cnt = 1;cnt * cnt <= num;++cnt){
		//Check if the counter evenly divides the number
		//If it does the counter and the other number are both divisors
		if((num % cnt) == 0){
			if(!isFound(cnt, divisors)){
				divisors.push_back(cnt);
			}
			if(!isFound(num/cnt, divisors)){
				divisors.push_back(num / cnt);
			}
		}
	}
	std::sort(divisors.begin(), divisors.end());
	return divisors;
}

template <class T>
T getSum(std::vector<T> numbers){
	T sum = 0;
	for(unsigned int cnt = 0;cnt < numbers.size();++cnt){
		sum += numbers.at(cnt);
	}
	return sum;
}

template<class T>
bool isFound(T num, std::vector<T> list){
	for(int cnt = 0;cnt < list.size();++cnt){
		if(list.at(cnt) == num){
			return true;
		}
	}
	return false;
}

std::vector<std::string> getPermutations(std::string master, int num){
	std::vector<std::string> perms;
	//Check if the number is out of bounds
	if((num >= master.size()) || (num < 0)){
		return perms;
	}
	//If this is the last possible recurse just return the current string
	else if(num == (master.size() - 1)){
		perms.push_back(master);
		return perms;
	}
	//If there are more possible recurses, recurse with the current permutation
	std::vector<std::string> temp;
	temp = getPermutations(master, num + 1);
	perms.insert(perms.end(), temp.begin(), temp.end());
	//You need to swap the current letter with every possible letter after it
	//The ones needed to swap before will happen automatically when the function recurses
	for(int cnt = 1;(num + cnt) < master.size();++cnt){
		std::swap(master[num], master[num + cnt]);
		temp = getPermutations(master, num + 1);
		perms.insert(perms.end(), temp.begin(), temp.end());
		std::swap(master[num], master[num + cnt]);
	}

	//The array is not necessarily in alpha-numeric order. So if this is the full array sort it before returning
	if(num == 0){
		std::sort(perms.begin(), perms.end());
	}
	return perms;
}

uint64_t getFib(uint64_t num){
	//Make sure the number is within bounds
	if(num <= 2){
		return 1;
	}
	//Setup the variables
	uint64_t fib = 0;
	uint64_t tempNums[3];
	tempNums[0] = tempNums[1] = 1;

	//Do the calculation
	for(uint64_t cnt = 2;cnt < num;++cnt){
		tempNums[cnt % 3] = tempNums[(cnt + 1) % 3] + tempNums[(cnt + 2) % 3];
	}
	fib = tempNums[(num - 1) % 3];	//Transfer the answer to permanent variable. -1 to account for the offset of starting at 0
	return fib;
}

mpz_class getMpzFib(uint64_t num){
	//Make sure the number is within bounds
	if(num <= 0){
		return 0;
	}
	else if(num <= 2){
		return 1;
	}
	mpz_class fibNum = 0;
	mpz_class tempNums[3];
	//Initialize the variables
	tempNums[0] = 1;
	tempNums[1] = 1;

	//Do the calculation
	for(uint64_t cnt = 2;cnt < num;++cnt){
		tempNums[cnt % 3] = tempNums[(cnt + 1) % 3] + tempNums[(cnt + 2) % 3];
	}

	return tempNums[(num - 1) % 3];	//Return the answer
}

//This is a function that performs a bubble sort on a vector
template<class T>
bool bubbleSort(std::vector<T> nums){
	bool notFinished = true;	//A flag to determine if the loop is finished
	for(int numLoops = 0;notFinished;++numLoops){	//Loop until you finish
		notFinished = false;	//Assume you are finished until you find an element out of order	
		//Loop through every element in the vector, moving the largest one to the end
		for(int cnt = 0;cnt < ((nums.size() - 1) - numLoops);++cnt){	//use size - 1 to make sure you don't go out of bounds
			if(nums.at(cnt) > nums.at(cnt + 1)){
				std::swap(nums.at(cnt), nums.at(cnt + 1));
				notFinished = true;
			}
		}
	}
}

//This is a function that perfomrs a quick sort on a vector
template<class T>
bool quickSort(std::vector<T> nums){
	
}

//This is a function that performs a search on a vector and returns the subscript of the item being searched for
template<class T>
int64_t search(std::vector<T> nums, T num){
	int64_t subscript = 0;	//Start with the subscript at 0
	//Step through every element in the vector and return the subscript if you find the correct element
	while(subscript < nums.size()){
		if(nums.at(subscript) == num){
			return subscript;
		}
	}
	//If you cannot find the element return -1
	return -1;
}

//This function finds the smallest element in a vector
template<class T>
T findMin(std::vector<T> arr){
	T min;	//For the smallest element

	//Make sure the vector is not empty
	if(arr.size() > 0){
		//Use the first element as the smallest element
		min = arr.at(0);
		//Run through every element in the vector, checking it against the current minimum
		for(int cnt = 1;cnt < arr.size();++cnt){
			//If the current element is smaller than the minimum, make it the new minimum
			if(arr.at(cnt) < min){
				min = arr.at(cnt);
			}
		}
	}

	//Return the element
	return min;
}

//This function finds the largest element in a vector
template<class T>
T findMax(std::vector<T> arr){
	T max;	//For the largest element

	//Make sure the vector is not empty
	if(arr.size() > 0){
		//Use the first element as the largest element
		max = arr.at(0);
		//Run through every element in the vector, checking it against the current minimum
		for(int cnt = 1;cnt < arr.size();++cnt){
			//If the current element is larger than the maximum, make it the new maximum
			if(arr.at(cnt) > max){
				max = arr.at(cnt);
			}
		}
	}

	//Return the element
	return max;
}

}


#endif //MEE_ALGORITHMS_HPP