Sorting Algorithms

merge_sort.cpp

/*
Author - Vinit Shahdeo
Check here - https://code.hackerearth.com/ad6725j
*/
#include <iostream>
using namespace std;
void printArray(int a[],int n)
{
    for(int i=0;i<n;i++)
    cout<<a[i]<<" ";
}
void merge(int a[],int l,int m,int r)
{
    int n1=m-l+1;
    int n2=r-m;
    int L[n1],R[n2];
    for(int i=0;i<n1;i++)
    {
        L[i]=a[l+i];
    }
    for(int j=0;j<n2;j++)
    {
        R[j]=a[m+1+j];
    }
    int i=0,j=0,k=l;
    while(i<n1 && j<n2)
    {
        if(L[i]<=R[j])
        {
            a[k]=L[i];
            i++;
        }
        else
        {
            a[k]=R[j];
            j++;
        }
        k++;
    }
    while(i<n1)
    {
        a[k]=L[i];
        i++;
        k++;
    }
    while(j<n2)
    {
        a[k]=R[j];
        j++;
        k++;
    }
}
void mergeSort(int a[],int l,int r)
{
    if(l<r)
    {
        int m=(l+r)/2;
        mergeSort(a,l,m);
        mergeSort(a,m+1,r);
        merge(a,l,m,r);
    }
}
int main()
{
    int n;
    cin>>n;
    int a[n];
    for(int i=0;i<n;i++)
    {
        cin>>a[i];
    }
    mergeSort(a,0,n-1);
    cout<<"\n Array after sorting : ";
    printArray(a,n);
    cout<<endl;
    return 0;
}

min_swap.cpp

#include <bits/stdc++.h>

using namespace std;

vector<string> split_string(string);

// Complete the minimumSwaps function below.
// minimum swaps in selection sort

int minimumSwaps(vector<int> arr) {
  
    int min_index;
    int count=0;
    for(int i=0;i<arr.size()-1;i++)
    {
        min_index=i;
        for(int j=i+1;j<arr.size();j++)
        {
            if(arr[min_index]>arr[j])
                min_index=j;
        }
        if(min_index!=i)
        {
            count++;
            swap(arr[i],arr[min_index]);
        }
    }
    for(int i=0;i<arr.size();i++)
        cout<<arr[i]<<" ";
    return count;
}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    int n;
    cin >> n;
    cin.ignore(numeric_limits<streamsize>::max(), '\n');

    string arr_temp_temp;
    getline(cin, arr_temp_temp);

    vector<string> arr_temp = split_string(arr_temp_temp);

    vector<int> arr(n);

    for (int i = 0; i < n; i++) {
        int arr_item = stoi(arr_temp[i]);

        arr[i] = arr_item;
    }

    int res = minimumSwaps(arr);

    fout << res << "\n";

    fout.close();

    return 0;
}

vector<string> split_string(string input_string) {
    string::iterator new_end = unique(input_string.begin(), input_string.end(), [] (const char &x, const char &y) {
        return x == y and x == ' ';
    });

    input_string.erase(new_end, input_string.end());

    while (input_string[input_string.length() - 1] == ' ') {
        input_string.pop_back();
    }

    vector<string> splits;
    char delimiter = ' ';

    size_t i = 0;
    size_t pos = input_string.find(delimiter);

    while (pos != string::npos) {
        splits.push_back(input_string.substr(i, pos - i));

        i = pos + 1;
        pos = input_string.find(delimiter, i);
    }

    splits.push_back(input_string.substr(i, min(pos, input_string.length()) - i + 1));

    return splits;
}