Climbing Stairs Problem in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return the base case for 1 step.

DSA C

if (n == 1) return [1];

Drag options to blanks, or click blank then click option'

A2

B0

Cn

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Returning 0 instead of 1 for the base case.

Returning n which is unnecessary here.

When there is only 1 step, there is exactly 1 way to climb it.

2fill in blank

medium

Complete the code to return the base case for 2 steps.

DSA C

if (n == 2) return [1];

Drag options to blanks, or click blank then click option'

A1

B3

C2

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Returning 1 instead of 2 for the base case.

Returning n which is 2 but not explained.

For 2 steps, you can climb as (1+1) or (2), so 2 ways.

3fill in blank

hard

Fix the error in the recursive return statement to correctly sum the ways.

DSA C

return climbStairs(n [1] 1) + climbStairs(n [1] 2);

Drag options to blanks, or click blank then click option'

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of - causing incorrect recursion.

Using * or / which are not valid here.

We subtract 1 and 2 from n to find ways to climb remaining steps.

4fill in blank

hard

Fill both blanks to create a loop that fills dp array for climbing stairs.

DSA C

for (int i = 3; i <= n; i++) {
    dp[i] = dp[i [1] 1] + dp[i [2] 2];
}

Drag options to blanks, or click blank then click option'

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or multiplication instead of subtraction in indices.

Mixing operators causing wrong dp indexing.

We subtract 1 and 2 to get previous dp values to sum.

5fill in blank

hard

Fill all three blanks to initialize dp array and return the final result.

DSA C

int dp[n+1];
dp[1] = [1];
dp[2] = [2];
return dp[[3]];

Drag options to blanks, or click blank then click option'

A1

B2

Cn

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Returning dp[0] or dp[1] instead of dp[n].

Incorrect base values for dp[1] or dp[2].

dp[1] = 1 way, dp[2] = 2 ways, return dp[n] for total ways.