Missing.cpp

//Given an array containing elements from 1 to 100 except one element in this range is missing.Find the missing element.
#include <stdio.h>

int main() {
    // Initialize an array with 99 elements (from 1 to 100 with one missing)
    int arr[99] = {
        1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
        11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
        21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
        31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
        41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
        51, 52, 53, 54, 55, 56, 57, 58, 59, 60,
        61, 62, 63, 64, 65, 66, 67, 68, 69, 70,
        71, 72, 73, 74, 75, 76, 77, 78, 79, 80,
        81, 82, 83, 84, 85, 86, 87, 88, 89, 90,
        91, 92, 93, 94, 95, 96, 97, 98, 100 // Missing 99
    };

    // Calculate the sum of numbers from 1 to 100 using the formula n*(n+1)/2
    int n = 100;
    int expected_sum = n * (n + 1) / 2;

    // Calculate the sum of elements in the array
    int actual_sum = 0;
    for (int i = 0; i < 99; i++) {
        actual_sum += arr[i];
    }

    // The missing element is the difference between the expected sum and the actual sum
    int missing_element = expected_sum - actual_sum;

    // Print the missing element
    printf("The missing element is: %d\n", missing_element);

    return 0; // End of the main function
}