Count number of digits after decimal on dividing a number

07 Jul, 2021
We are given two numbers A and B. We need to calculate the number of digits after decimal. If in case the numbers are irrational then print “INF”.Examples: 
Input  : x = 5, y = 3
Output : INF
5/3 = 1.666....

Input :  x = 3, y = 6
Output : 1
3/6 = 0.5 
The idea is simple we follow school division and keep track of remainders while dividing one by one. If remainder becomes 0, we return count of digits seen after decimal. If remainder repeats, we return INF.  
C++
Java
Python3
C#
Javascript
// CPP program to count digits after dot when a// number is divided by another.#include <bits/stdc++.h>using namespace std; int count(int x, int y){    int ans = 0;  // Initialize result         unordered_map<int, int> m;         // calculating remainder    while (x % y != 0) {         x = x % y;         ans++;         // if this remainder appeared before then        // the numbers are irrational and would not        // converge to a solution the digits after        // decimal will be infinite        if (m.find(x) != m.end())            return -1;         m[x] = 1;        x = x * 10;    }    return ans;} // Driver codeint main(){    int res = count(1, 2);    (res == -1)? cout << "INF" : cout << res;     cout << endl;    res = count(5, 3);    (res == -1)? cout << "INF" : cout << res;     cout << endl;    res = count(3, 5);    (res == -1)? cout << "INF" : cout << res;    return 0;}
// Java program to count digits after dot when a// number is divided by another.import java.util.*; class GFG{ static int count(int x, int y){    int ans = 0; // Initialize result         Map<Integer,Integer> m = new HashMap<>();         // calculating remainder    while (x % y != 0)    {         x = x % y;         ans++;         // if this remainder appeared before then        // the numbers are irrational and would not        // converge to a solution the digits after        // decimal will be infinite        if (m.containsKey(x))            return -1;         m.put(x, 1);        x = x * 10;    }    return ans;} // Driver codepublic static void main(String[] args){    int res = count(1, 2);    if((res == -1))        System.out.println("INF");    else        System.out.println(res);     res = count(5, 3);    if((res == -1))        System.out.println("INF");    else        System.out.println(res);         res = count(3, 5);    if((res == -1))        System.out.println("INF");    else        System.out.println(res);}} // This code is contributed by Rajput-Ji
# Python3 program to count digits after dot# when a number is divided by another.def count(x, y):    ans = 0 # Initialize result     m = dict()     # calculating remainder    while x % y != 0:        x %= y         ans += 1         # if this remainder appeared before then        # the numbers are irrational and would not        # converge to a solution the digits after        # decimal will be infinite        if x in m:            return -1         m[x] = 1        x *= 10     return ans # Driver Codeif __name__ == "__main__":    res = count(1, 2)     print("INF") if res == -1 else print(res)     res = count(5, 3)    print("INF") if res == -1 else print(res)     res = count(3, 5)    print("INF") if res == -1 else print(res) # This code is contributed by# sanjeev2552
// C# program to count digits after dot when a// number is divided by another.using System;using System.Collections.Generic;     class GFG{ static int count(int x, int y){    int ans = 0; // Initialize result         Dictionary<int,int> m = new Dictionary<int,int>();         // calculating remainder    while (x % y != 0)    {         x = x % y;         ans++;         // if this remainder appeared before then        // the numbers are irrational and would not        // converge to a solution the digits after        // decimal will be infinite        if (m.ContainsKey(x))            return -1;         m.Add(x, 1);        x = x * 10;    }    return ans;} // Driver codepublic static void Main(String[] args){    int res = count(1, 2);    if((res == -1))        Console.WriteLine("INF");    else        Console.WriteLine(res);     res = count(5, 3);    if((res == -1))        Console.WriteLine("INF");    else        Console.WriteLine(res);         res = count(3, 5);    if((res == -1))        Console.WriteLine("INF");    else        Console.WriteLine(res);}} // This code is contributed by 29AjayKumar
<script> // JavaScript program to count digits after dot when a// number is divided by another. function count(x,y){    let ans = 0; // Initialize result    let m = new Map();    // calculating remainder    while (x % y != 0)    {          x = x % y;          ans++;          // if this remainder appeared before then        // the numbers are irrational and would not        // converge to a solution the digits after        // decimal will be infinite        if (m.has(x))            return -1;          m.set(x, 1);        x = x * 10;    }    return ans;} // Driver codelet res = count(1, 2);    if((res == -1))        document.write("INF"+"<br>");    else        document.write(res+"<br>");      res = count(5, 3);    if((res == -1))        document.write("INF"+"<br>");    else        document.write(res+"<br>");          res = count(3, 5);    if((res == -1))        document.write("INF"+"<br>");    else        document.write(res+"<br>");  // This code is contributed by rag2127 </script>
Output: 
1
INF
1
Time Complexity: O(N * log(N) )
Auxiliary Space: O(N)
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Rajput-Ji
29AjayKumar
sanjeev2552
ujjwalgoel1103
rag2127
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