Preet Patel patelpreet422

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Changing the world for better

patelpreet422 / iterative_bsearch.cpp

Created October 27, 2018 09:39

	#include <iostream>
	#include <algorithm>
	#include <vector>
	using namespace std;

	bool binary_search(vector<int>::iterator lower, vector<int>::iterator upper, int k)
	{
	auto mid = next(lower, distance(lower, upper)/2);
	while(lower <= upper)
	{

patelpreet422 / set_rightmost_off.cpp

Created October 24, 2018 17:32

Setting rightmost set bit of a number to zero.

	#include <iostream>
	#include <cstdio>
	using namespace std;
	unsigned long set_rightmost_bit_off(unsigned long k)
	{
	return k&(k-1);
	}
	int main()
	{
	cout << set_rightmost_bit_off(6ul) << '\n';

patelpreet422 / r2d_d2r_converter.cpp

Created July 19, 2018 19:18

Roman to decimal and decimal to roman number converter

	#include <iostream>
	#include <cctype>
	#include <array>
	#include <unordered_map>
	using namespace std;

	static unordered_map<char, int> roman_to_dec {
	{'I', 1},
	{'V', 5},
	{'X', 10},

patelpreet422 / factorial.cpp

Last active June 9, 2018 19:31

Factorial of large numbers

	#include <iostream>
	#include <algorithm>
	#include <string>
	#include <chrono>
	using namespace std::chrono;
	const int limit = 200;
	const std::string factorial(int n)
	{
	std::string res(limit, '0');
	res[0] = '1';

patelpreet422 / permutation.cpp

Last active June 7, 2018 21:03

Permutation in C++

	#include <iostream>
	#include <string>
	#include <algorithm>
	void permuteHelper(std::string s, std::string chosen)
	{
	if (s.empty())
	{
	std::cout << chosen << '\n';
	return;
	}

patelpreet422 / kadanes_algorithm.cpp

Last active June 8, 2018 03:44

Maximum sum sub-array

	#include <iostream>
	#include <algorithm>
	#include <climits>
	#include <tuple>
	using namespace std;
	tuple<int, int, int> maxsumsubarray(int *arr, int size)
	{
	int start = 0, end = size-1, max_sum=INT_MIN, sum = 0;
	for(int i = 0; i < size; ++i)
	{

patelpreet422 / recursive_bsearch.cpp

Last active June 6, 2018 12:26

Recursive binary search

	#include <iostream>
	#include <algorithm>
	using namespace std;

	bool binarySearchHelper(int key, int *array, int low, int high){
	if(low == high) return array[low] == key;
	if(low < high) {
	int mid = (low + high)/2;
	if(array[mid] == key) return true;
	else if(array[mid] > key) return binarySearchHelper(key, array, low, mid);

patelpreet422 / recursive_palindrome.cpp

Last active June 7, 2018 21:12

Palindrome using recursion

	#include <iostream>
	#include <string>
	using namespace std;

	bool isPalindrome(const string &str, int low, int high)
	{
	if (low >= high)return true;
	if (str[low] != str[high])return false;
	return isPalindrome(str, ++low, --high);
	}

patelpreet422 / towerofhanoi.cpp

Created May 8, 2018 05:36

Tower of hanoi

	#include <iostream>
	void toh(char from, char to, char intermediate, int noofdisk)
	{
	if(noofdisk == 1)
	std::cout << "Move " << noofdisk << " from " << from << " to " << to << '\n';
	else {
	toh(from, intermediate, to, noofdisk-1);
	std::cout << "Move " << noofdisk << " from " << from << " to " << to << '\n';
	toh(intermediate, to, from, noofdisk-1);
	}

patelpreet422 / lattice.cpp

Created May 7, 2018 20:10

Lattice path

	#include <map>
	#include <iostream>
	#include <algorithm>
	unsigned long long moveto(const std::pair<int, int> &p, std::map< std::pair<int, int>, unsigned long long> &memo)
	{
	if(memo.find(p) != memo.end()) return memo[p];

	/*
	(0, 0) -> (0, 0) => We are already at our destiny so, no of ways we can reach our destiny is '0'
	(0, 0) -> (a, 0) => Only '1' way to reach any point on X-axis from origin