Balanced Parentheses Problem Using Stack in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to push an element onto the stack.

DSA C

void push(char stack[], int *top, char value) {
    stack[++(*top)] = [1];
}

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

Astack

B*top

Cvalue

Dtop

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*top' instead of 'value' to push.

Using 'stack' or 'top' incorrectly.

We push the given value onto the stack at the incremented top index.

2fill in blank

medium

Complete the code to check if the stack is empty.

DSA C

int isEmpty(int top) {
    return [1] == -1;
}

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

Astack

Btop

Cvalue

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Checking 'stack' or 'value' instead of 'top'.

Using 'size' which is unrelated here.

The stack is empty when 'top' is -1.

3fill in blank

hard

Fix the error in the pop function to return the top element and update the top index.

DSA C

char pop(char stack[], int *top) {
    if (*top == -1) return '\0';
    return stack[[1]--];
}

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

A(*top)

Btop

Cstack

D*top

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'top' instead of '*top' causes wrong indexing.

Using 'stack' or '(*top)' incorrectly.

We return the element at '*top' and then decrement '*top'.

4fill in blank

hard

Fill both blanks to check if the popped opening bracket matches the current closing bracket.

DSA C

int isMatchingPair(char opening, char closing) {
    return (opening == [1] && closing == [2]) ||
           (opening == '{' && closing == '}') ||
           (opening == '[' && closing == ']');
}

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

A'('

B'['

C')'

D']'

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing opening and closing brackets.

Using double quotes instead of single quotes.

We check if opening is '(' and closing is ')'.

5fill in blank

hard

Fill all three blanks to complete the main loop that checks balanced parentheses.

DSA C

for (int i = 0; i < length; i++) {
    if (expression[i] == [1] || expression[i] == [2] || expression[i] == [3]) {
        push(stack, &top, expression[i]);
    } else {
        if (isEmpty(top)) return 0;
        char popped = pop(stack, &top);
        if (!isMatchingPair(popped, expression[i])) return 0;
    }
}

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

A'('

B'['

C'{'

D')'

Attempts:

3 left

💡 Hint

Common Mistakes

Including closing brackets in the push condition.

Using wrong bracket characters.

We push opening brackets '(', '[', '{' onto the stack.