How to join two Arrays using STL in C++?
Given two arrays, join these two arrays using STL in C++. Example:
Input: arr1[] = {1, 45, 54, 71, 76, 12}, arr2[] = {1, 7, 5, 4, 6, 12} Output: {1, 4, 5, 6, 7, 12, 45, 54, 71, 76} Input: arr1[] = {1, 7, 5, 4, 6, 12}, arr2[] = {10, 12, 11} Output: {1, 4, 5, 6, 7, 10, 11, 12}
Approach: Joining can be done with the help of set_union() function provided in STL. Syntax:
set_union (InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result);
Below is the implementation of the above approach:
CPP
#include <bits/stdc++.h>
using namespace std;
int main()
{
int arr1[] = { 1, 45, 54, 71, 76, 12 };
int arr2[] = { 1, 7, 5, 4, 6, 12 };
int n1 = sizeof (arr1) / sizeof (arr1[0]);
int n2 = sizeof (arr2) / sizeof (arr2[0]);
sort(arr1, arr1 + n1);
sort(arr2, arr2 + n2);
cout << "First Array: " ;
for ( int i = 0; i < n1; i++)
cout << arr1[i] << " " ;
cout << endl;
cout << "Second Array: " ;
for ( int i = 0; i < n2; i++)
cout << arr2[i] << " " ;
cout << endl;
vector< int > v(n1 + n2);
vector< int >::iterator it, st;
it = set_union(arr1, arr1 + n1,
arr2, arr2 + n2,
v.begin());
cout << "\nAfter joining:\n" ;
for (st = v.begin(); st != it; ++st)
cout << *st << ", " ;
cout << '\n' ;
return 0;
}
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Output:
First Array: 1 12 45 54 71 76
Second Array: 1 4 5 6 7 12
After joining:
1, 4, 5, 6, 7, 12, 45, 54, 71, 76,
Time Complexity: O(nlogn)
Auxiliary Space: O(n)
Last Updated :
07 Jul, 2022
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