• Dec 24, 2021 •aedrarian
3 likes • 21 views
/* 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; }
• Nov 18, 2022 •AustinLeath
0 likes • 0 views
using namespace std; class Hash { int BUCKET; // No. of buckets // Pointer to an array containing buckets list<int> *table; public: Hash(int V); // Constructor // inserts a key into hash table void insertItem(int x); // deletes a key from hash table void deleteItem(int key); // hash function to map values to key int hashFunction(int x) { return (x % BUCKET); } void displayHash(); }; Hash::Hash(int b) { this->BUCKET = b; table = new list<int>[BUCKET]; } void Hash::insertItem(int key) { int index = hashFunction(key); table[index].push_back(key); } void Hash::deleteItem(int key) { // get the hash index of key int index = hashFunction(key); // find the key in (inex)th list list <int> :: iterator i; for (i = table[index].begin(); i != table[index].end(); i++) { if (*i == key) break; } // if key is found in hash table, remove it if (i != table[index].end()) table[index].erase(i); } // function to display hash table void Hash::displayHash() { for (int i = 0; i < BUCKET; i++) { cout << i; for (auto x : table[i]) cout << " --> " << x; cout << endl; } } // Driver program int main() { // array that contains keys to be mapped int a[] = {15, 11, 27, 8, 12}; int n = sizeof(a)/sizeof(a[0]); // insert the keys into the hash table Hash h(7); // 7 is count of buckets in // hash table for (int i = 0; i < n; i++) h.insertItem(a[i]); // delete 12 from hash table h.deleteItem(12); // display the Hash table h.displayHash(); return 0; }
• Oct 23, 2022 •LeifMessinger
0 likes • 1 view
//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), [¤tBitmask](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; }
• Apr 16, 2023 •LeifMessinger
#include <iostream> #include <string> //Should already be in iostream #include <cstdlib> //A word score adds up the character values. a-z gets mapped to 1-26 for the values of the characters. //wordScore [wordValue] //Pipe in the input into stdin, or type the words yourself. //Lowercase words only int characterValue(const char b){ return ((b >= 'a') && (b <= 'z'))? ((b - 'a') + 1) : 0; } int main(int argc, char** argv){ //The first argument specifies if you are trying to look for a certain word score int wordValue = (argc > 1)? std::atoi(argv[1]) : 0; std::string line; while(std::getline(std::cin, line)){ int sum = 0; for(const char c : line){ sum += characterValue(c); } if(wordValue){ //If wordValue is 0 or the sum is the correct value if(wordValue == sum){ std::cout << line << std::endl; } } else { std::cout << sum << "\t" << line << std::endl; } } return 0; }
• Aug 25, 2023 •LeifMessinger
1 like • 12 views
#include <iostream> int main(){ const char* const hello = "Hello, world!"; const char* bruh = hello; char* const yeet = hello; std::cout << bruh << std::endl; std::cout << yeet << std::endl; return 0; } /* Place your bets! Will the program: a.) Print "Hello, world!" twice? b.) Compile error on line 5 (bruh initialize line) because the pointer gets implicit cast to non-const? c.) Compile error on line 7 (yeet initialize line) because the char gets implicit cast to non-const? d.) Both b and c? e.) Compile error line 11 (print yeet) because the pointer is constant and can't be incremented f.) Print "Hello, world!" then print the pointer address in hexadecimal g.) Both b and e? h.) Both c and e? i.) B, c, and e? */ // The answer is in this base 64 string: // 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
• Jul 30, 2023 •LeifMessinger
1 like • 6 views
//Constant prefix notation solver using bruh //Could make it infix or postfix later #include<string> #include<vector> #include<iostream> std::vector<long double> bruhBuff; long double operator ""bruh(long double a){ bruhBuff.push_back(a); return a; } long double operator ""bruh(const char op){ if(bruhBuff.size() < 2) throw "Bruh weak"; long double b = bruhBuff.back(); bruhBuff.pop_back(); long double a = bruhBuff.back(); bruhBuff.pop_back(); switch(op){ case (int)('+'): return a + b; case (int)('-'): return a - b; case (int)('*'): return a * b; case (int)('/'): return a / b; } return 69l; } int main(){ 1.0bruh; 2.0bruh; std::cout << '+'bruh << std::endl; return 0; }