Merge_Sort.cpp

#include <iostream>
#include <vector>
using namespace std;

void merge(vector<int>& vec, int left, int mid, int right) {
    int n1 = mid - left + 1;
    int n2 = right - mid;
    vector<int> leftVec(n1), rightVec(n2);

    for (int i = 0; i < n1; i++)
        leftVec[i] = vec[left + i];
    for (int j = 0; j < n2; j++)
        rightVec[j] = vec[mid + 1 + j];

    int i = 0, j = 0, k = left;
    while (i < n1 && j < n2) {
        if (leftVec[i] <= rightVec[j])
            vec[k++] = leftVec[i++];
        else
            vec[k++] = rightVec[j++];
    }

    while (i < n1)
        vec[k++] = leftVec[i++];
    while (j < n2)
        vec[k++] = rightVec[j++];
}

void mergeSort(vector<int>& vec, int left, int right) {
    if (left < right) {
        int mid = left + (right - left) / 2;
        mergeSort(vec, left, mid);
        mergeSort(vec, mid + 1, right);
        merge(vec, left, mid, right);
    }
}

int main() {
    vector<int> vec = {12, 11, 13, 5, 6, 7};
    int n = vec.size();
    mergeSort(vec, 0, n - 1);
    for (auto i : vec) {
        cout << i << " ";
    }
    return 0;
}