triplets_with_0_sum.txt

// Function to find triplets with zero sum.

/**
 * @param {number[]} arr
 * @param {number} n
 * @returns {boolean}
*/

function findTriplets(arr, n)
{
	// your code here
	// naive approach: 3 nested loops and compare intersecting sum = 0;

	// more intelligent approach: reduce to a pair sum problem
	// This involves traversing through the array.
	// For every element arr[i], find a pair with sum “-arr[i]”.

	var found = false;
	var combos = []
	for (var i = 0; i < n - 1; i++) {
	    var elements = new Set() // add current element to compare against pair combos
	    // iterate through comninations of sum pairs
	    // if the current elemen matches the negative of the pair we are done
	    for (var j = i + 1; j < n; j++) {
		var x = -(arr[i] + arr[j]);

		if (elements.has(x)) { found = true; combos.push([x, arr[i], arr[j]])}
		else elements.add(arr[j])
	    } 
	}
	// console.log('combos', combos)
	return found === false ? 0 : 1
}

findTriplets([0, -1, 1, 2, -3, 1, 9, 7, 6], 9)