min_pairs.cpp

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

void min_pair(vector<int> a1,vector<int> a2){


	sort(a2.begin(),a2.end());

	int p1,p2;
	int diff = INT_MAX;

	//iterate over 1 array and look for closes elements in the second array
	for(int x : a1){
		auto lb = lower_bound(a2.begin(),a2.end(),x) - a2.begin();

		//left
		if(lb>=1 and x - a2[lb-1] < diff){
			diff = x - a2[lb-1];
			p2 = x;
			p1 = a2[lb-1];
		}
		//greater / right
		if(lb!=a2.size() and a2[lb]-x < diff){
			diff = a2[lb] - x;
			p1 = x;
			p2 = a2[lb];
		}

	}
	cout<<"Min Pair "<<p1<<" and "<<p2 <<endl;
	return;

}


int  main(){

	vector<int> a1 = {-1, 5, 10, 20, 3};
	vector<int> a2 = {26, 134, 135, 15, 17};
	min_pair(a1,a2);


	return 0;
}