Find max of two Rational numbers

Given two Rational numbers, the task is to find the maximum of given two rational numbers.

Examples :

Input : first = 3/4, second= 3/2
Output : 3/2

Input : first = 100/100, second = 300/400
Output : 100/100

A simple solution is to find float values and compare the float values. The float computations may cause precision errors. We can avoid them using below approach.

Say first = 3/2, second = 3/4

  • First take a LCM of (4, 2) which is denominator of rational number. so the LCM of this is 4, then divide with both denominator and multiple with numerator of first and second respectively so the denominator value is first numerator = 6, second numerator = 3.
  • Then find the max between these two. so here first numerator is max then print first rational number.




// CPP program to find max between
// two Rational numbers
#include <bits/stdc++.h>
using namespace std;
struct Rational
    int nume, deno;
// Get lcm of two number's
int lcm(int a, int b) 
    return (a * b) / (__gcd(a, b));
// Get max rational number
Rational maxRational(Rational first, Rational sec)
    // Find the LCM of first->denominator
    // and sec->denominator
    int k = lcm(first.deno, sec.deno);
    // Declare nume1 and nume2 for get the value of
    // first numerator and second numerator
    int nume1 = first.nume;
    int nume2 = sec.nume;
    nume1 *= k / (first.deno);
    nume2 *= k / (sec.deno);
    return (nume2 < nume1)? first : sec;
// Driver Code
int main()
    Rational first = { 3, 2 };
    Rational sec = { 3, 4 };
    Rational res = maxRational(first, sec);
    cout << res.nume << "/" << res.deno;
    return 0;


Output :


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