Question

Write an algorithm that determines whether the given 4 digit number is "lucky" or not. A number is "lucky" when the sum of the first two digits is equal to the sum of the last two digits.

Answer 1

Explanation:

Input: n = 983

Output: true

All digits are different

Input: n = 9838

Output: false

8 appears twice

// C++ program to check if a given number is lucky

#include<iostream>

using namespace std;

// This function returns true if n is lucky

bool isLucky(int n)

{

// Create an array of size 10 and initialize all

// elements as false. This array is used to check

// if a digit is already seen or not.

bool arr[10];

for (int i=0; i<10; i++)

arr[i] = false;

// Traverse through all digits of given number

while (n > 0)

{

// Find the last digit

int digit = n%10;

// If digit is already seen, return false

if (arr[digit])

return false;

// Mark this digit as seen

arr[digit] = true;

// REmove the last digit from number

n = n/10;

}

return true;

}