started on unsorted array function (previous was sorted)

This commit is contained in:
Francis Yang 2024-01-09 08:00:58 -08:00
parent a46cc24527
commit 44f3b4cc2f

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@ -41,34 +41,48 @@ export function twinPointerSorted(sortedArray, seekElement, comparatorCallback)
return [0, 0]; return [0, 0];
} }
// An example of a twin pointer method on an unsorted array. /* An example of a twin pointer method on an unsorted array. In this problem, we aim to get the heighest possible area from two numbers,
export function twinPointerUnsorted(sortedArray, seekElement, comparatorCallback) { assuming that each number n is a rectangle of 1 width and n height. (Problem and solution taken from Leetcode #11)
*/
/**
*
* @param {*[]} unsortedArray
* @param {function(a, b)} [comparatorCallback]
* @return {number}
*/
export function twinPointerUnsorted(unsortedArray, comparatorCallback) {
const comparator = new Comparator(comparatorCallback); const comparator = new Comparator(comparatorCallback);
// These variables will be our pointers; since the array is sorted, we can set them to the left and rightmost elements. // Again, we set our two pointers to the left and rightmost elements of the array.
let left = 0; let left = 0;
let right = sortedArray.length - 1 let right = unsortedArray.length - 1;
// If our left and right pointers have met then we have iterated through the entire array. // We initialize two area variables; one for our current area between our two pointers and one for the highest that we'll return.
while (left < right) { let area = 0;
let mostArea = 0;
/** // Functionally equivalent to the while conditional we set in the first example.
* If our sum is less than the target then we can increase said sum but by increasing the left value; while (left !== right) {
* since the array is sorted, this will always result in array[left] becoming a larger number.
*/
if (comparator.lessThan(sortedArray[left] + sortedarray[right], seekElement)) {
left++;
// Same concept as before, only now we decrease our sum because it's greater than the target. // In this situation, since we don't have a specific "target" in mind we instead compare the two values at our two pointers to each other.
} else if (comparator.greaterThan(sortedArray[left] + sortedarray[right], seekElement)) { if (height[left] < height[right]) {
right--;
// Assuming we have found our target, return left and right since they represent the indices that our correct sum is located at. // Here we simply calculate our current area and whether we need to change our highest area by comparing it with the current.
} else { area = (Math.min(height[left], height[right]) * (right - left));
return [left, right] mostArea = Math.max(area, mostArea);
}
/**
* Again, we move the left pointer forward or the right pointer backwards. You may be thinking that
*/
left++;
} else {
area = (Math.min(height[left], height[right]) * (right - left));
mostArea = Math.max(area, mostArea);
right--;
}
} }
// Return [0, 0] (an impossible answer due to our while loop) if we haven't found any combination of numbers that works. return mostArea
return [0, 0];
} }