Two Number Sum.cpp

TwONumberSum.cpp

#include <vector>
#include <unordered_set>
using namespace std;

// Repasado 2 veces
vector<int> twoNumberSum(vector<int> array, int targetSum) {
	unordered_set<int> targets;
	for (int i = 0; i < array.size(); i++) {
		int y = targetSum - array[i];
		if (targets.find(y) != targets.end()) {
			return vector<int> { array[i], y };
		} else {
			targets.insert(array[i]);	
		}
	}
  return {};
}

2 number sums

Solution 1

Use the diffrerene from the target and your current element, use a hash function to check wether exist.

Solution 3

Use a left pointer and a right pointer, if lower increment left and if gigher decrement right.