Merge_Sort.cpp

#include<bits/stdc++.h>
using namespace std;
void merge(vector<int>& a, int Start, int Mid, int End)
{
    vector<int> temp(End - Start + 1);
    int i = Start;
    int j = Mid + 1;
    int k = 0;
    while (i <= Mid && j <= End)
    {
        if (a[i] < a[j])//swap (a[i],a[j])//swapping
        {
            temp[k] = a[i];
            i++;
        }
        else
        {
            temp[k] = a[j];
            j++;
        }
        k++;
    }
    while (i <= Mid)
    {
        temp[k] = a[i];
        k++;
        i++;
    }
    while (j <= End)
    {
        temp[k] = a[j];
        k++;
        j++;
    }
    for ( i = Start; i <= End; i++)
    {
        a[i] = temp[i - Start];
    }
}
void mergesort(vector<int>& a, int start, int end)
{
    if (start < end)
    {
        int mid = (start + end) / 2;
        mergesort(a, start, mid);
        mergesort(a, mid + 1, end);
        //assumed that these two functions had been already solved:: Sorted
        //Merge these sorted arrays into final one.
        merge(a, start, mid, end);
    }
}
int main()
{
    int n; cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; i++)
    {
        cin >> a[i];
    }
    mergesort(a, 0, n - 1);
    for (int i = 0; i < n; i++)
    {
        cout << a[i] << " ";
    }
    return 0;
}