Quick Sort in C++

Published on 28 April 2022 (Updated: 25 September 2022)

Quick Sort in C++

Welcome to the Quick Sort in C++ page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

#include <iostream>
#include <bits/stdc++.h>
 
using namespace std;

void handle_error(){
	cout<<"Usage: please provide a list of at least two integers to sort in the format \"1, 2, 3, 4, 5\""<<endl;
	exit(0);
}

int check(string s){
	int x1=0,x2=s.size()-1;
	for(int i=0;i<s.size();i++){
		if(s[i]!=' '){
			x1=i;
			break;
		}
	}
	for(int i=s.size()-1;i>=x1;i--){
		if(s[i]!=' '){
			x2=i;
			break;
		}
	}
	for(int i=x1;i<=x2;i++){
		if(s[i]==' '){
			handle_error();
		}
	}

	return stoi(s);
}

vector<int> convert(string s){
	vector<int> v;
	string num="";
	for(int i=0;i<s.size();i++){
		if((int)s[i]>=48 && (int)s[i]<=57 || s[i]==' '){
			num+=s[i];
		}else if(s[i]==','){
			v.push_back(check(num));
			num="";
		}else{
			handle_error();	
		}
	}
	if(num.size()>0){
		v.push_back(check(num));
	}
	return v;
}

int partition1(vector<int> &a,int l,int u)
{
    int v,i,j,temp;
    v=a[l];
    i=l;
    j=u+1;
    do
    {
        do
            i++;    
        while(a[i]<v&&i<=u);        
        do
            j--;
        while(v<a[j]);        
        if(i<j)
        {
            temp=a[i];
            a[i]=a[j];
            a[j]=temp;
        }
    }while(i<j);    
    a[l]=a[j];
    a[j]=v;
    return(j);
}

void quick_sort(vector<int> &a,int l,int u)
{
    int j;
    if(l<u)
    {
        j=partition1(a,l,u);
        quick_sort(a,l,j-1);
        quick_sort(a,j+1,u);
    }
}

int main(int argc,char* argv[]){
	if(argc<2){
		handle_error();
	}
	vector<int> v=convert(argv[1]);
	if(v.size()<2){
		cout<<"Usage: please provide a list of at least two integers to sort in the format \"1, 2, 3, 4, 5\""<<endl;
		exit(0);
	}
	int n=v.size();
	int min_idx;
	quick_sort(v,0,n-1);
	for(int i=0;i<n-1;i++){
		cout<<v[i]<<", ";
	}
	cout<<v[n-1];
}

Quick Sort in C++ was written by:

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

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How to Run the Solution

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