Question

Write code for a function that uses a loop to compute the sum of all integers from 1 to n. Do a time analysis, counting each basic operation (such as assignment and ++) as one operation.

Answer 1

Answer:

#include<bits/stdc++.h>  

using namespace std;  

int sumOfinteger(int );  

  // Returns sum of all digits in numbers from 1 to n  

int sumOfintegersFrom1ToN(int n)  {  

   int result = 0; // initialize result  

    // One by one compute sum of digits in every number from  

   // 1 to n  

   for (int x = 1; x <= n; x++)  

       result += sumOfinteger(x);  

   return result;  

}  

  // A utility function to compute sum of digits in a  

// given number x  

int sumOfinteger(int x)  {  

   int sum = 0;  

   while (x != 0)  {  

      sum += x %10;  

       x   = x /10;  }  

   return sum;  }  

  // Driver Program  

int main()  {  

   int n ;  

   cout<<"enter a number between 1 and n : ";

   cin>>n;

   cout << "Sum of digits in numbers from 1 to " << n << " is " << sumOfDigitsFrom1ToN(n);  

   return 0;  }