DATA STRUCTURES PROGRAM • HEAPS, HASHING & DISJOINT SETS

Delete the Root from a Min-Heap

Learn how to delete the root from a min-heap using a clear C program.

IntermediateMin-heapExtract minimumHeapify down

PROBLEM UNDERSTANDING

Input and expected output

Sample input

No input required

Sample output

Removed = 5
Heap: 10 30 20 40

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int main(void)
{
    int heap[] = {5, 10, 20, 30, 40};
    int size = 5, minimum = heap[0];
    heap[0] = heap[--size];
    int position = 0;
    while (1) {
        int left = 2 * position + 1, right = left + 1, smallest = position;
        if (left < size && heap[left] < heap[smallest]) smallest = left;
        if (right < size && heap[right] < heap[smallest]) smallest = right;
        if (smallest == position) break;
        int temporary = heap[position]; heap[position] = heap[smallest]; heap[smallest] = temporary;
        position = smallest;
    }
    printf("Removed = %d\nHeap: ", minimum);
    for (int index = 0; index < size; index++) printf("%d ", heap[index]);
    putchar('\n');
    return 0;
}

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EXPECTED OUTPUT FOR THE SAMPLE

Removed = 5
Heap: 10 30 20 40

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Move the final value to the root and swap it down with its smaller child.
Display the computed result.

Move the final value to the root and swap it down with its smaller child.

EFFICIENCY

Time and space complexity

Time complexity

O(log n)

Auxiliary space

O(n)

DEBUGGING CHECKLIST

Common mistakes

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Use the correct format specifier for every variable.

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Initialize variables before using their values.

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Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.