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
// C++ program to join two Arrays // using set_union() in STL #include <bits/stdc++.h> using namespace std; int main() { // Get the array int arr1[] = { 1, 45, 54, 71, 76, 12 }; int arr2[] = { 1, 7, 5, 4, 6, 12 }; // Compute the sizes int n1 = sizeof (arr1) / sizeof (arr1[0]); int n2 = sizeof (arr2) / sizeof (arr2[0]); // Sort the arrays sort(arr1, arr1 + n1); sort(arr2, arr2 + n2); // Print the array 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; // Initialise a vector // to store the merged values // and an iterator // to traverse this vector vector< int > v(n1 + n2); vector< int >::iterator it, st; it = set_union(arr1, arr1 + n1, arr2, arr2 + n2, v.begin()); // Print the merged array cout << "\nAfter joining:\n" ; for (st = v.begin(); st != it; ++st) cout << *st << ", " ; cout << '\n' ; return 0; } |
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)
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