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Hash Table Example

Nov 18, 2022AustinLeath
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More C++ Posts

Simple Greedy sort C++

Jun 30, 2023Iceman_71

0 likes • 7 views

#include <iostream>
using namespace std;
int main()
{
int arr[] = {5, 1, 4, 20, 10, 2, 13, 11, 6, 21};
int greed[] = {0, 0, 0, 0};
int k = 0;
int i;
int set_index;
while (k < 4)
{
i = 0;
while (i < 10)
{
if (arr[i] > greed[k])
{
greed[k] = arr[i];
set_index = i;
}
i++;
}
arr[set_index] = 0;
k++;
}
cout << greed[0] << " " << greed[1] << " " << greed[2] << " " << greed[3] << endl;
}

Test

Jun 17, 2024oceantran27

0 likes • 2 views

#include <iostream>
using namespace std;
int main {
cout << 1;
}

set hostname syscall

Oct 7, 2023AustinLeath

0 likes • 12 views

#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;
}

GCD using Stein's Algorithm

Jun 30, 2023Iceman_71

1 like • 6 views

// Iterative C++ program to
// implement Stein's Algorithm
//#include <bits/stdc++.h>
#include <bitset>
using namespace std;
// Function to implement
// Stein's Algorithm
int gcd(int a, int b)
{
/* GCD(0, b) == b; GCD(a, 0) == a,
GCD(0, 0) == 0 */
if (a == 0)
return b;
if (b == 0)
return a;
/*Finding K, where K is the
greatest power of 2
that divides both a and b. */
int k;
for (k = 0; ((a | b) & 1) == 0; ++k)
{
a >>= 1;
b >>= 1;
}
/* Dividing a by 2 until a becomes odd */
while ((a & 1) == 0)
a >>= 1;
/* From here on, 'a' is always odd. */
do
{
/* If b is even, remove all factor of 2 in b */
while ((b & 1) == 0)
b >>= 1;
/* Now a and b are both odd.
Swap if necessary so a <= b,
then set b = b - a (which is even).*/
if (a > b)
swap(a, b); // Swap u and v.
b = (b - a);
} while (b != 0);
/* restore common factors of 2 */
return a << k;
}
// Driver code
int main()
{
int a = 12, b = 780;
printf("Gcd of given numbers is %d\n", gcd(a, b));
return 0;
}

Bit arithmetic + and -

Sep 1, 2023LeifMessinger

0 likes • 2 views

#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;
}

C++ Scanner

Jul 16, 2024LeifMessinger

0 likes • 12 views

//===============Header File==================
#include <iostream>
#include <sstream> //stringbuf
#include <utility> //exchange
//Couple rules:
//Characters given through the getter functions have to be removed from the buffer.
//This is so that bufferEmpty() == buffer.in_avail() > 0 basically always.
//skipWhitespace doesn't remove the text from the buffer, but it does return the number of characters.
//nextWord will trim whitespace before the word
//nextInt will trim non-numbers before the number
//hasNextInt and hasNextWord will trim the whitespace. If you think you need it, you should get nextWhitespace before doing any of those.
//Whitespace after a word or an int is left on the buffer.
//nextWhitespace will (get and) remove whitespace until the end of the line, including the newline character, but stops before the next line.
//nextWhitespace won't read the next line when called before the end of the line, and it won't prompt the user for the next line if interactive.
//If nextWhitespace is called after reading the end of the line, then it will read a new line into the buffer, which will prompt the user.
//It acts like nextLine, but if there's something non-whitespace on the current line it stops there.
class Scanner {
public:
std::stringbuf buffer;
std::istream& input;
Scanner(std::istream& in = std::cin) : buffer(), input(in) {}
//Buffer debugging
bool fillBuffer();
bool bufferEmpty();
void printBufferEmpty();
std::string getBuffer();
size_t bufferLength();
void printBufferStats();
//Int
bool hasNextInt();
int nextInt();
//Word
bool hasNextWord();
std::string nextWord();
//Line
bool hasNextLine();
//Whitespace
size_t skipWhitespace(); //Prob should be private, but I don't believe in that private shit.
bool hasNextWhitespace();
std::string nextWhitespace();
std::string nextWhitespaceAll();
std::string nextLine();
};
//===============Source File==================
bool Scanner::fillBuffer() { //Returns if it had to get the next line from the input.
const bool badInput = input.eof() || input.bad();
const bool shouldFillBuffer = bufferEmpty() && !badInput;
if (shouldFillBuffer) {
std::string line;
if (std::getline(input, line)) {
buffer.str(buffer.str() + line + "\n");
}
}
return shouldFillBuffer;
}
bool Scanner::bufferEmpty(){
return buffer.str() == "";
}
void Scanner::printBufferEmpty(){
std::cout << "The buffer is " << (bufferEmpty()? "" : "not") << " empty." << std::endl;
}
std::string Scanner::getBuffer(){
return buffer.str();
}
size_t Scanner::bufferLength(){
return buffer.str().length();
}
void Scanner::printBufferStats(){
if(bufferEmpty()){
std::cout << "The buffer is \"\"" << std::endl;
return;
}
std::cout << "The length of the buffer is " << bufferLength() << std::endl;
if(buffer.sgetc() == '\r'){
std::cout << "The buffer is \\r\\n" << std::endl;
}else if(buffer.sgetc() == '\n'){
std::cout << "The buffer is \\n" << std::endl;
}
}
bool Scanner::hasNextInt() {
return hasNextWord() && (std::isdigit(buffer.sgetc()) || buffer.sgetc() == '-');
}
int Scanner::nextInt() {
if (!hasNextInt()) { //Will fill the buffer if not filled. Will also trim whitespace.
return 0;
}
std::string num;
size_t charactersRead = 0;
while (buffer.in_avail() > 0 && (std::isdigit(buffer.sgetc()) || buffer.sgetc() == '-')) {
num += buffer.sbumpc();
++charactersRead;
}
buffer.str(buffer.str().erase(0, charactersRead));
return std::stoi(num);
}
bool Scanner::hasNextWord() {
nextWhitespaceAll();
return buffer.in_avail() > 0;
}
std::string Scanner::nextWord() {
if (!hasNextWord()) { //Will fill the buffer if not filled. Will also trim whitespace.
return "";
}
std::string word;
size_t charactersRead = 0;
while (buffer.in_avail() > 0 && !std::isspace(buffer.sgetc())) {
word += buffer.sbumpc();
++charactersRead;
}
buffer.str(buffer.str().erase(0, charactersRead));
return word;
}
bool Scanner::hasNextLine() {
return (!bufferEmpty()) || fillBuffer();
}
size_t Scanner::skipWhitespace() { //Returns characters read
size_t charactersRead = 0;
while (buffer.in_avail() > 0 && std::isspace(buffer.sgetc())) {
buffer.sbumpc();
++charactersRead;
}
return charactersRead;
}
bool Scanner::hasNextWhitespace(){
fillBuffer();
return buffer.in_avail() > 0 && std::isspace(buffer.sgetc());
}
std::string Scanner::nextWhitespace() {
if (!hasNextWhitespace()) { //Will fill the buffer if not filled
return "";
}
const size_t charactersRead = skipWhitespace();
std::string whitespace = buffer.str().substr(charactersRead);
buffer.str(buffer.str().erase(0, charactersRead));
return whitespace;
}
std::string Scanner::nextWhitespaceAll(){
std::string whitespace;
while(hasNextWhitespace()){
std::string gottenWhiteSpace = nextWhitespace();
whitespace += gottenWhiteSpace;
}
return whitespace;
}
std::string Scanner::nextLine(){
if (!hasNextLine()) {
return "";
}
fillBuffer();
//Swap out the old buffer with an empty buffer, and get the old buffer as a variable.
std::string line = std::exchange(buffer, std::stringbuf()).str();
//Remove the newline.
if(line[line.length() - 1] == '\n' || line[line.length() - 1] == '\r' ) line.pop_back();
if(line[line.length() - 1] == '\r' || line[line.length() - 1] == '\n' ) line.pop_back();
return line;
}
//=================Word and Int test=================
while(bruh.hasNextInt() || bruh.hasNextWord()){
std::cout << "started loop" << std::endl;
if(bruh.hasNextInt()){
std::cout << "Int: " << bruh.nextInt() << " " << std::endl;
}else{
std::cout << "Word: " << bruh.nextWord() << " " << std::endl;
}
bruh.nextWhitespace();
}
//===================Line test======================
for(int count = 1; bruh.hasNextLine(); ++count){
std::string line = bruh.nextLine();
std::cout << "Line " << count << ": " << line << std::endl;
}