Tabulation Bottom Up DP in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the DP array with zeros.

DSA Typescript

const dp: number[] = new Array(n + 1).fill([1]);

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A1

B-1

C0

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of 0 causes incorrect base values.

Using null or -1 can cause runtime errors in calculations.

We fill the dp array with 0 because initially no subproblems are solved.

2fill in blank

medium

Complete the code to set the base case for the DP array.

DSA Typescript

dp[0] = [1];

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An

B1

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Setting dp[0] to 0 means no ways to make sum zero, which is incorrect.

Setting dp[0] to n or -1 is logically wrong for base case.

Setting dp[0] = 1 means there is exactly one way to reach sum zero: by choosing nothing.

3fill in blank

hard

Fix the error in the loop condition to correctly iterate over sums.

DSA Typescript

for (let sum = 1; sum [1]= target; sum++) {

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A<

B>=

C>

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using < excludes the target sum from calculation.

Using > or >= causes the loop to never run or run incorrectly.

The loop must include the target sum, so use <= to cover all sums up to target.

4fill in blank

hard

Fill both blanks to update the DP array correctly inside the nested loop.

DSA Typescript

if (sum >= nums[i]) {
  dp[sum] = dp[sum] + dp[sum [1] nums[i]];
}

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A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of - causes wrong indexing and errors.

Using * or / is not meaningful in this context.

We subtract nums[i] from sum to find the previous state to add ways from.

5fill in blank

hard

Fill all three blanks to complete the tabulation function for subset sum count.

DSA Typescript

function countSubsets(nums: number[], target: number): number {
  const dp: number[] = new Array(target + 1).fill([1]);
  dp[0] = [2];
  for (let i = 0; i < nums.length; i++) {
    for (let sum = target; sum >= [3]; sum--) {
      if (sum >= nums[i]) {
        dp[sum] += dp[sum - nums[i]];
      }
    }
  }
  return dp[target];
}

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A0

B1

Cnums[i]

Dtarget

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing dp with 1 instead of 0 causes wrong counts.

Setting dp[0] to 0 means no base case.

Iterating sums forward causes overcounting.

Initialize dp with 0, set dp[0] = 1 for base case, and iterate sums down from target to nums[i] to avoid reuse in the same iteration.