Exercises   Set - 4 - Solutions

1. In the following program, replace the iterative function by an equivalent recursive function:

#include<iostream>
using namespace std;

void iterative_fn(int n);

int main() {
  int n;
  cout<<"Enter a positive  int\n";
  cin>>n;
  cout<<"\n";
  iterative_fn(n);

}


void iterative_fn(int n){
   for (int i=n; i>0;i--){
     cout<<i<<endl;
   }
}

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2. Write a recursive function gcd that returns the greatest common divisor of $x$ and $y$, which is defined recursively as follows: If $y$ is equal to 0, then $gcd(x,y)$ is $x$; otherwise $gcd(x,y)$ is $gcd(y, x$% $y)$, where % is the modulus operator.

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3. Write a function triangle(unsigned int m, unsigned int n) with the following properties:

  void triangle(unsigned int m, unsigned int n)

  // Precondition: m <= n
  // Postcondition: The function has printed a pattern of 2*(n-m+1) lines
  // to the output stream outs. The first line contains m asterisks, the next
  // line contains m+1 asterisks, and so on up to a line with n asterisks.
  // Then the pattern is repeated backwards, going n back down to m.

  /* Example output:
     triangle(3, 5) will print this to cout:
     ***
     ****
     *****
     *****
     ****
     ***
  */

Try to understand this first

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