Kth Smallest Element Using Min Heap in DSA C++ - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a min heap from the vector.

DSA C++

std::priority_queue<int, std::vector<int>, [1]> minHeap(nums.begin(), nums.end());

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Astd::greater<int>

Bstd::less<int>

Cstd::equal_to<int>

Dstd::not_equal_to<int>

Attempts:

3 left

💡 Hint

Common Mistakes

Using std::less creates a max heap, not a min heap.

Forgetting to specify the comparator leads to max heap behavior.

The min heap in C++ priority_queue is created by using std::greater<int> as the comparison function.

2fill in blank

medium

Complete the code to pop the smallest element from the min heap.

DSA C++

minHeap.[1]();

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Aremove

Bdelete

Cpop

Dextract

Attempts:

3 left

💡 Hint

Common Mistakes

Using remove or delete which are not valid methods for priority_queue.

Trying to erase elements by value instead of popping the top.

Use pop() to remove the top (smallest) element from the priority_queue.

3fill in blank

hard

Fix the error in the code to get the kth smallest element from the min heap.

DSA C++

for (int i = 1; i < [1]; ++i) {
    minHeap.pop();
}
return minHeap.top();

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Ak

Bk-1

Ck*2

Dk+1

Attempts:

3 left

💡 Hint

Common Mistakes

Using k-1 in the loop condition causes one less pop than needed.

Using k+1 or k*2 causes too many pops and wrong result.

We pop (k-1) times to remove the first (k-1) smallest elements, then the top is the kth smallest. The loop runs from 1 to k-1, so condition is i < k.

4fill in blank

hard

Fill both blanks to complete the function that returns the kth smallest element using a min heap.

DSA C++

int kthSmallest(std::vector<int>& nums, int k) {
    std::priority_queue<int, std::vector<int>, [1]> minHeap(nums.begin(), nums.end());
    for (int i = 1; i < [2]; ++i) {
        minHeap.pop();
    }
    return minHeap.top();
}

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Astd::greater<int>

Bk

Ck-1

Dstd::less<int>

Attempts:

3 left

💡 Hint

Common Mistakes

Using std::less creates max heap, wrong for kth smallest.

Looping until i < k-1 pops too few elements.

The min heap uses std::greater<int>. The loop runs while i < k to pop (k-1) elements.

5fill in blank

hard

Fill all three blanks to create a function that returns the kth smallest element using a min heap and handles empty input.

DSA C++

int kthSmallest(std::vector<int>& nums, int k) {
    if (nums.empty() || k > nums.size()) return -1;
    std::priority_queue<int, std::vector<int>, [1]> minHeap(nums.begin(), nums.end());
    for (int i = 1; i < [2]; ++i) {
        minHeap.[3]();
    }
    return minHeap.top();
}

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

Astd::greater<int>

Bk

Cpop

Dstd::less<int>

Attempts:

3 left

💡 Hint

Common Mistakes

Not checking for empty input or k out of range.

Using wrong comparator or wrong method to remove elements.

Use std::greater<int> for min heap, loop until i < k, and call pop() to remove elements.