A Collection of Code Snippets in as Many Programming Languages as Possible
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Welcome to the Merge Sort in C++ page! Here, you'll find the source code for this program as well as a description of how the program works.
#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;
}
void merge(int low, int mid, int high, vector<int> &v)
{
int n1 = mid - low + 1;
int n2 = high - mid;
vector<int> v1(n1), v2(n2);
for (int i = 0; i < n1; i++)
{
v1[i] = v[i + low];
}
for (int i = 0; i < n2; i++)
{
v2[i] = v[i + mid + 1];
}
int j = 0, k = 0;
int l = low;
while (j < n1 && k < n2)
{
if (v1[j] < v2[k])
{
v[l] = v1[j];
j++;
}
else
{
v[l] = v2[k];
k++;
}
l++;
}
while (j < n1)
{
v[l] = v1[j];
j++;
l++;
}
while (k < n2)
{
v[l] = v2[k];
k++;
l++;
}
}
void mergesort(int low, int high, vector<int> &v)
{
if (low < high)
{
int mid = (low + high) / 2;
mergesort(low, mid, v);
mergesort(mid + 1, high, v);
merge(low, mid, high, v);
}
}
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;
mergesort(0, n - 1, v);
for (int i = 0; i < n - 1; i++)
{
cout << v[i] << ", ";
}
cout << v[n - 1];
}
Merge Sort in C++ was written by:
If you see anything you'd like to change or update, please consider contributing.
Note: The solution shown above is the current solution in the Sample Programs repository as of Oct 10 2022 16:05:09. The solution was first committed on Oct 26 2019 08:19:51. As a result, documentation below may be outdated.
No 'How to Implement the Solution' section available. Please consider contributing.
No 'How to Run the Solution' section available. Please consider contributing.