C++ Programming Code Examples
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Simple Merge Sort Program in C++
/* Simple Merge Sort Program in C++
Merge sort is an O(n log n) comparison-based sorting algorithm. Most implementations produce a stable sort, which means that the implementation preserves the input order of equal elements in the sorted output. Conceptually, a merge sort works as: Divide the unsorted list into n sublists, each containing 1 element and repeatedly merge sublists to produce new sorted sublists until there is only 1 sublist remaining. This will be the sorted list. */
#include <iostream>
#include<conio.h>
#include<stdlib.h>
#define maxsize 5
using namespace std;
void merge_sort(int, int);
void merge_array(int, int, int, int);
int arr_sort[maxsize];
int main() {
int i;
cout << "Simple C++ Merge Sort Example - Functions and Array\n";
cout << "\nEnter " << maxsize << " Elements for Sorting : " << endl;
for (i = 0; i < maxsize; i++)
cin >> arr_sort[i];
cout << "\nYour Data :";
for (i = 0; i < maxsize; i++) {
cout << "\t" << arr_sort[i];
}
merge_sort(0, maxsize - 1);
cout << "\n\nSorted Data :";
for (i = 0; i < maxsize; i++) {
cout << "\t" << arr_sort[i];
}
getch();
}
void merge_sort(int i, int j) {
int m;
if (i < j) {
m = (i + j) / 2;
merge_sort(i, m);
merge_sort(m + 1, j);
// Merging two arrays
merge_array(i, m, m + 1, j);
}
}
void merge_array(int a, int b, int c, int d) {
int t[50];
int i = a, j = c, k = 0;
while (i <= b && j <= d) {
if (arr_sort[i] < arr_sort[j])
t[k++] = arr_sort[i++];
else
t[k++] = arr_sort[j++];
}
//collect remaining elements
while (i <= b)
t[k++] = arr_sort[i++];
while (j <= d)
t[k++] = arr_sort[j++];
for (i = a, j = 0; i <= d; i++, j++)
arr_sort[i] = t[j];
}
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