Created
October 1, 2017 00:31
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highestProductOf3 = function (arrayOfInts) { | |
if(arrayOfInts.length < 3){ // if provided array has less than 3 values then return false | |
console.log('Less than 3 items!'); | |
return false; | |
} | |
// we're going to start at the 3rd item (at index 2) | |
// so pre-populate highests and lowests based on the first 2 items. | |
// we could also start these as null and check below if they're set | |
// but this is arguably cleaner | |
var highest = Math.max(arrayOfInts[0], arrayOfInts[1]); | |
var lowest = Math.min(arrayOfInts[0], arrayOfInts[1]); | |
var highestProductOf2 = arrayOfInts[0] * arrayOfInts[1]; | |
var lowestProductOf2 = arrayOfInts[0] * arrayOfInts[1]; | |
// except this one--we pre-populate it for the first *3* items. | |
// this means in our first pass it'll check against itself, which is fine. | |
var highestProductOf3 = arrayOfInts[0] * arrayOfInts[1] * arrayOfInts[2]; | |
// walk through items, starting at index 2 | |
for (var i = 2; i < arrayOfInts.length; i++) { | |
var current = arrayOfInts[i]; | |
// do we have a new highest product of 3? | |
// it's either the current highest, | |
// or the current times the highest product of two | |
// or the current times the lowest product of two | |
highestProductOf3 = Math.max(Math.max(highestProductOf3, current * highestProductOf2), current * lowestProductOf2); | |
// do we have a new highest product of two? | |
highestProductOf2 = Math.max(Math.max(highestProductOf2, current * highest), current * lowest); | |
// do we have a new lowest product of two? | |
lowestProductOf2 = Math.min(Math.min(lowestProductOf2, current * highest), current * lowest); | |
// do we have a new highest? | |
highest = Math.max(highest, current); | |
// do we have a new lowest? | |
lowest = Math.min(lowest, current); | |
} | |
; | |
return highestProductOf3; | |
}; | |
var arr = [1,25,50]; // a test ! | |
var res = highestProductOf3(arr); | |
console.log(res); // console log result ! |
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