# Largest number less than N with digit sum greater than the digit sum of N in C++

In this tutorial, we are going to write a program that finds the number less than N with digit sum greater than the digit sum of n.

Let's see the steps to solve the problem.

• Write a function to find the digits sum.
• Initialise n.
• Write a loop that iterates from n - 1 to 1.
• Check the digits sum of current number with the digits sum of n.
• If the digits sum of current number is greater than n, then return the current number.
• Move to the next number.

## Example

Let's see the code.

Live Demo

#include <bits/stdc++.h>
using namespace std;
int sumOfDigits(int n) {
int digitsSum = 0;
while (n > 0) {
digitsSum += n % 10;
n /= 10;
}
return digitsSum;
}
int findLargestNumber(int n) {
int i = n - 1;
while (i > 0) {
if (sumOfDigits(i) > sumOfDigits(n)) {
return i;
}
i--;
}
return -1;
}
int main() {
int n = 75;
cout << findLargestNumber(n) << endl;
return 0;
}

## Output

If you run the above code, then you will get the following result.

69

## Conclusion

If you have any queries in the tutorial, mention them in the comment section.