Feat : Subset Sum using DP

[Suryac72]

Hi @appgurueu @raklaptudirm please review my PR. I added subset sum problem using DP

[appgurueu]

Why is the indentation off?

[appgurueu]

setLength is redundant, just use set.length.

[TruongNhanNguyen]

I would like to suggest that the function prototype should be like this:

Suggested change

	export function isSubsetSum(set: number[], setLength: number, sum: number): boolean {
	export function isSubsetSum(set: number[], sum: number): boolean {

[appgurueu]

Please try to give this a proper name, like subsetExists, and add some comment that explains that subsetExists[n][sum] is whether there exists a subset using up to the first n elements in set that sums up to sum.

[appgurueu]

This base case could use a comment (something along the lines of "empty subset sums up to 0")

[appgurueu]

This "recursion" formula should be explained.

[TruongNhanNguyen]

What do you think about this suggestion @appgurueu, @Suryac72

Suggested change

	const dp: boolean[][] = new Array(setLength + 1);
	for (let i = 0; i <= setLength; i++) {
	dp[i] = new Array(sum + 1).fill(false);
	}
	// subsetExists[n][sum] indicates whether there exists a subset using up to the first n elements in set
	// that sums up to sum.
	const subsetExists: boolean[][] = Array.from({ length: set.length + 1 }, () => Array(sum + 1).fill(false));

[TruongNhanNguyen]

Suggested change

	for (let i = 0; i <= setLength; i++) {
	dp[i][0] = true;
	}
	// Base case: when sum is 0, there's always an empty subset.
	for (let i = 0; i <= set.length; i++) {
	subsetExists[i][0] = true;
	}

[TruongNhanNguyen]

Suggested change

	for (let i = 1; i <= setLength; i++) {
	for (let j = 1; j <= sum; j++) {
	if (set[i - 1] > j) {
	dp[i][j] = dp[i - 1][j];
	} else {
	dp[i][j] = dp[i - 1][j] || dp[i - 1][j - set[i - 1]];
	}
	}
	}
	return dp[setLength][sum];
	for (let currentIndex = 1; currentIndex <= set.length; currentIndex++) {
	const currentElement = set[currentIndex - 1];
	for (let currentSum = 1; currentSum <= sum; currentSum++) {
	if (currentElement > currentSum) {
	// If the current element is greater than the current sum,
	// exclude the current element from the subset.
	subsetExists[currentIndex][currentSum] = subsetExists[currentIndex - 1][currentSum];
	} else {
	// Either include or exclude the current element in the subset.
	subsetExists[currentIndex][currentSum] = subsetExists[currentIndex - 1][currentSum] || subsetExists[currentIndex - 1][currentSum - currentElement];
	}
	}
	}
	return subsetExists[set.length][sum];