Return to Answer

1. Flambino's answer shows there's no need to continue enumeration if current index is bigger than the matching values' max index found already.
2. Jodrell's answer shows it's possible to do everything in just one loop, pointed out by Jonah.

1. Flambino's answer shows there's no need to continue enumeration if current index is bigger than the matching values' max index found already.
2. Jodrell's answer shows it's possible to do everything in just one loop, pointed out by Jonah.

var sum_pairs = function(ints, s) {
 var last = ints.length - 1, 
 map = {},
 pair, pairMaxIndex = last;
 for (var i = 0; i <= pairMaxIndex; i++) {
 var a = ints[i];
 var b = s - a;
 var j = map[b];
 if (j !== undefined && i <= pairMaxIndex && j <= pairMaxIndex) {
 pairMaxIndex = i > j ? i : j;
 pair = i < j ? [a, b] : [b, a];
 }
 var tmp = map[a];
 if (tmp === undefined || i < tmp) {
 map[a] = i;
 }
 }
 return pair;
};

var sum_pairs = function(ints, s) {
 var map = {},
 pair, pairMaxIndex = ints.length - 1;
 for (var i = 0; i <= pairMaxIndex; i++) {
 var a = ints[i];
 var b = s - a;
 var j = map[b];
 if (j !== undefined && i <= pairMaxIndex && j <= pairMaxIndex) {
 pairMaxIndex = i > j ? i : j;
 pair = i < j ? [a, b] : [b, a];
 }
 var tmp = map[a];
 if (tmp === undefined || i < tmp) {
 map[a] = i;
 }
 }
 return pair;
};

var sum_pairs = function(ints, s) {
 var last = ints.length - 1, 
 map = {},
 pair, pairMaxIndex = last + last;
 for (var i = 0; i <= last && i < pairMaxIndex; i++) {
 var a = ints[i];
 var b = s - a;
 var j = map[b];
 if (j !== undefined && i < pairMaxIndex && j < pairMaxIndex) {
 pairMaxIndex = i > j ? i : j;
 pair = i < j ? [a, b, i, j] : [b, a, j, i];
 }
 var tmp = map[a];
 if (tmp === undefined || i < tmp) {
 map[a] = i;
 }
 }
 return pair;
};

var sum_pairs = function(ints, s) {
 var last = ints.length - 1, 
 map = {},
 pair, pairMaxIndex = last;
 for (var i = 0; i <= pairMaxIndex; i++) {
 var a = ints[i];
 var b = s - a;
 var j = map[b];
 if (j !== undefined && i <= pairMaxIndex && j <= pairMaxIndex) {
 pairMaxIndex = i > j ? i : j;
 pair = i < j ? [a, b] : [b, a];
 }
 var tmp = map[a];
 if (tmp === undefined || i < tmp) {
 map[a] = i;
 }
 }
 return pair;
};