Largest Rectangle in Histogram Using Stack in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the stack pointer.

DSA C

int stack[1000];
int top = [1];

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

A-1

B0

C1

D1000

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing top to 0 causes off-by-one errors.

Using a large number like 1000 causes invalid stack state.

The stack pointer 'top' should start at -1 to indicate the stack is empty.

2fill in blank

medium

Complete the code to push an index onto the stack.

DSA C

stack[++top] = [1];

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

Aheight[i]

Bi

Ctop

Dstack[top]

Attempts:

3 left

💡 Hint

Common Mistakes

Pushing height[i] instead of index causes wrong calculations.

Pushing top or stack[top] is incorrect.

We push the current index 'i' onto the stack, not the height value.

3fill in blank

hard

Fix the error in the condition to pop from stack when current height is less.

DSA C

while (top != -1 && height[stack[top]] [1] height[i]) {
    // pop and calculate area
}

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

A>

B<

C==

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' causes no popping and wrong area calculation.

Using '==' or '>=' changes logic incorrectly.

We pop when the height at stack top is greater than current height to find smaller bars.

4fill in blank

hard

Fill both blanks to calculate width correctly after popping from stack.

DSA C

int width = top == -1 ? [1] : [2] - stack[top] - 1;

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

Ai

Ctop

Dstack[top]

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'top' or 'stack[top]' instead of 'i' causes wrong width.

Not subtracting 1 leads to off-by-one errors.

If stack is empty, width is current index i; else width is difference between i and new top index minus one.

5fill in blank

hard

Fill all three blanks to finalize max area calculation inside the loop.

DSA C

int height_popped = height[stack[top--]];
int width = top == -1 ? [1] : [2] - stack[top] - 1;
max_area = max(max_area, height_popped * [3]);

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

Ai

Cwidth

Dtop

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'top' instead of 'width' in area calculation.

Mixing up variables for width calculation.

Width is calculated same as before; max area updates with popped height times width.