## Hash Table Example

0 likes • Nov 18, 2022
C++

## More C++ Posts

```#include <bits/stdc++.h>#define MAXSIZE 50000#define INF 100000
using namespace std;
bool visited[MAXSIZE]; //Checks if a node is visited or not in BFS and DFSbool isConnected = true; //Checks if the input graph is connected or not
int dist[MAXSIZE], discover[MAXSIZE], finish[MAXSIZE]; //Distance for BFS, in time and out time for DFSint t = 1; //Time used for DFSint u, v, i, j, k, N = 0;
stack<int> st; //Stack for TopSort
multiset<pair<int, int>> s; //collection of pairs to sort by distancepair<int, int> current; //pointer variable to a position in the multiset
void BFS(){	queue<int> q; //queue for BFS	q.push(1); //pushing the source	dist = 0; //assign the distance of source as 0	visited = 1; //marking as visited		while(!q.empty())	{	u = q.front();	q.pop();
if(!visited[v]) //if not visited, update the distance and push onto queue	{	visited[v] = 1;	dist[v] = dist[u]+1;	q.push(v);	}
}
}		for(i = 1; i <= N; i++)	{	s.insert(make_pair(dist[i], i)); //for sorted distance	}		cout << "BFS results:" << endl;		//prints BFS results and checks if the graph is connected	while(!s.empty())	{	current = *s.begin(); 	s.erase(s.begin());
i = current.second; 	j = current.first;
if(j == INF) //if any infinite value, graph is not connected	{	cout << i << " INF" << endl;	isConnected = false;	}	else	{	cout << i << " " << j << endl;	}
}
//marks blocks of memory as visited	memset(visited, 0, sizeof visited);}

void dfsSearch(int s){	visited[s] = 1; //marking it visited	discover[s] = t++; //assigning and incrementing time
int i, v;
if(!visited[v]) //if vertex is not visited then visit, else continue	{	dfsSearch(v);	}
}
st.push(s); //pushed onto stack for TopSort if it was called	finish[s] = t++; //out time}
void DFS(){
for(i = 1; i <= N; i++)	{	if(visited[i]) //if visited continue, else visit it with DFS	{	continue;	}
dfsSearch(i); //embedded function to actually perform DFS	}
for(i=1;i<=N;i++)	{	s.insert(make_pair(discover[i], i)); //minheap for sorted discovery time	}		cout << "DFS results:" << endl;
while(!s.empty()) //Prints DFS results as long as the multiset is not empty	{	current = *s.begin(); //duplicates the pointer to first object in the multiset	s.erase(s.begin()); //erases the first object in multiset
i = current.second;	cout << i << " " << discover[i] << " " << finish[i] << endl; //prints discover times and finish times	}
}
void TopSort(){	//call DFS so we can have a sorted stack to print	for(i=1;i<=N;i++)	{	if(visited[i])	{	continue;	}
dfsSearch(i);	}
cout<<"Topological Sort results:"<<endl;
//print sorted results from DFS	while(!st.empty())	{	i = st.top(); 	st.pop();
cout << i << endl;	}
//declare blocks of memory as visited	memset(visited, 0, sizeof visited);
}

int main(){	string str, num, input;	int selection, connectedChoice = 0;

//get to input any file, more freedom than declaring file in command line	cout << "Enter the exact name of your input file [case sensitive]: ";	cin >> input;		ifstream inputFile(input); //Read the input file
//checks if the ifstream cannot open	if(inputFile.fail())	{	cout << endl << "No input files matching that name. Terminating..." << endl;	return 0;	}
//Read until the end of file	while(!inputFile.eof())	{	getline(inputFile, str); //read the current line
if(str == "")	{	continue;	}
if(!isdigit(str)) //checks to see if the first item in a line is a digit or not	{	cout << "Invalid file format. You have a line beginning with a non-digit. Terminating..." << endl;	return 0;	}
stringstream ss;	ss << str; //convert the line to stream of strings		ss >> num; //read the line num	stringstream(num) >> u;		while(!ss.eof())	{	ss>>num;	if(stringstream(num) >> v)	{	adj[u].push_back(v); //read the adjacent vertices	}	}
N++; //calculate the number of vertices	sort(adj[u].begin(), adj[u].end()); //sort the adjacency list in case it is not sorted	}		//creates arbitrary values for distance, will check later if INF remain	for(i = 1; i <= N; i++)	{	dist[i] = INF;	}
cout << endl << "Valid Input file loaded!" << endl;
while(selection != 4)	{	cout << "************************************************" << endl;	cout << "What type of analysis would you like to perform?" << endl;	cout << "1: Breadth-First Search" << endl;	cout << "2: Depth-First Search" << endl;	cout << "3: Topological Sort" << endl;	cout << "4: Quit" << endl;	cout << "************************************************" << endl;		//read user input and execute selection	cin >> selection;
switch(selection)	{	case 1:	cout << endl;	BFS();	cout << endl;	cout << "Would you like to know if the graph is connected?" << endl;	cout << "1: Yes" << endl;	cout << "Any other key: No" << endl;	cin >> connectedChoice;
switch(connectedChoice)	{	case 1:	if(!isConnected)	{	cout << "The graph is not connected." << endl << endl;	}	else	{	cout << "The graph is connected!" << endl << endl;	}	break;	default:	break;	}	break;	case 2:	cout << endl;	DFS();	cout << endl;	break;	case 3:	cout << endl;	TopSort();	cout << endl;	break;	case 4:	return 0;	default:	cout << endl << "Invalid selection." << endl; //loops the selection prompt until a valid selection is input.	}
}	}```
```/*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{3, 4, -1, 1}, 4) << endl;	cout << calcMissing(new int{1, 2, 0}, 3) << endl;
//No positive numbers	cout << calcMissing(new int{0}, 1) << endl;}```
```#include <iostream>using namespace std;
main{	cout << "No tabbing. That's very sad :(\n";	cout << "No in-editor highlighting either :(((\n";	cout << "Descriptions might be niice too.";}```
```#include <iostream>using namespace std;
int main(){    cout << "Hello, World!" << endl;    return 0;}```
```#include <iostream>#include <cmath>#include <string.h>
using namespace std;
int main() {
string tickerName;    int numOfContracts;    float currentOptionValue;
cout << "Enter a stock ticker: ";    getline(cin, tickerName);
cout << "Enter the current number of " << tickerName << " contracts you are holding: ";    cin >> numOfContracts;

cout << "Enter the current price of the option: ";    cin >> currentOptionValue;

cout << "The value of your " << tickerName << " options are: \$" << (currentOptionValue * 100.00) * (numOfContracts);
cout << endl;
return 0;}```
```#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 onlyint 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) : 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;}```