Find array pairs whose sum is a given number

by bob m

HTML

<p id="sum">what's new</p>
<!--  // good answer at https://stackoverflow.com/questions/9656789/find-2-numbers-in-an-unsorted-array-equal-to-a-given-sum -->

JavaScript

function findSumPairs(ary, sum){
	ary.sort(function(a,b){	return a - b; });
  console.log('SORTED: ' + ary + '; Ary length is: ' + ary.length);
  // outer loop goes foward from 0, inner goes backward from len
  // if sum of two elements less than sum input, advance first loop
  // if sum is greater, advance second loop
  var numPairs=0;
  for (i=0; i<ary.length; i++){
  	for (y=ary.length-1; y>0; y--)
    { // we never want i and y to meet
    	if (i >= y){break;}	
      if (ary[i] + ary[y] < sum){ 
      	// outer+inner less than sum, advance outer 
      	break;
    	} 
			if (ary[i] + ary[y] == sum){ // we have a match !
      	console.log('SUM FOUND i y ' + i +' ' + y +' ' + ary[i] + '+' +ary[y]);
        numPairs++;
      }
		}
  }
  return numPairs;
}
var myAry=[5,1,7,6,4,9,10,15];
var sum = 10;
var res=findSumPairs(myAry, sum);
document.getElementById("sum").innerHTML = "Sorted array: " + myAry + '; Ary length is: ' + myAry.length + '; numPairs = ' + res;