Example: Find Second Smallest Element in C

// Find Second Smallest Element
#include <stdio.h>
#include <limits.h> // Required for INT_MAX

int main() {
    int arr[] = {12, 3, 1, 9, 5, 10, 1}; // Example array with a duplicate
    int n = sizeof(arr) / sizeof(arr[0]);

    // Step 1: Initialize firstSmallest and secondSmallest
    // We initialize them to INT_MAX (the largest possible integer value)
    // This ensures that any element in the array will be smaller than them.
    int firstSmallest = INT_MAX;
    int secondSmallest = INT_MAX;

    // Step 2: Handle edge cases for array size
    if (n < 2) {
        printf("Array should have at least two elements.\n");
        return 1; // Indicate an error or invalid input
    }

    // Step 3: Iterate through the array
    for (int i = 0; i < n; i++) {
        // If current element is smaller than firstSmallest
        if (arr[i] < firstSmallest) {
            // The old firstSmallest becomes the new secondSmallest
            secondSmallest = firstSmallest;
            // The current element becomes the new firstSmallest
            firstSmallest = arr[i];
        }
        // Else if current element is smaller than secondSmallest
        // AND it's not equal to firstSmallest (to handle duplicates)
        else if (arr[i] < secondSmallest && arr[i] != firstSmallest) {
            // The current element becomes the new secondSmallest
            secondSmallest = arr[i];
        }
    }

    // Step 4: Check if secondSmallest was found
    // If secondSmallest is still INT_MAX, it means all elements were identical
    // or there weren't enough distinct elements after firstSmallest.
    if (secondSmallest == INT_MAX) {
        printf("No second smallest element found (all elements might be same).\n");
    } else {
        printf("The smallest element is: %d\n", firstSmallest);
        printf("The second smallest element is: %d\n", secondSmallest);
    }

    return 0;
}