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Calculate the IST : Indian Standard Time
  • Last Updated : 03 May, 2021

Given two integer H and R where H is the time in hours at a place X and R is the distance in degrees from place X to India, the task is to find the current time in IST.
UTC (Coordinated Universal Time) is a 24-hour time standard that is used to synchronize world clocks.
Examples: 
 

Input: H = 24, R = 82.50 
Output: IST = 5:30 
IST = (24/360)* 82.50 
= 5.5 
= 0.5*60 (i.e 60 minute = 360 degree rotation and 1 minute = 6 degree so, 0.5 hour * 60 = 30) 
IST = 5:30
Input: H = 20, R = 150 
Output: IST = 8:20 
 

 

Approach: 
 

  • It is known that 1 hour = 60 minute = 360 degree rotation.
  • 1 degree rotation = (1 / 360) hour.
  • 2 degree rotation = (1 / 360) * 2 hour.
  • So, Generalised formula will be:

 



IST = UTC + (H / 360) * R (UTC = 0 for IST)
IST = ( H / 360 ) * R

The answer will be converted in 0:00 form so int part (hour) and float part in IST are separated and the float part is multiplied by 60 to convert it into minutes.
Below is the implementation of the above approach: 
 

C++




// C++ implementation of the approach
#include <cmath>
#include <iostream>
using namespace std;
 
// Function to calculate Indian Standard Time
void cal_IST(int h, float r)
{
    float IST = (h * r * 1.0) / 360;
 
    // Separate integer part
    int int_IST = (int)IST;
 
    // Separate float part and return ceil value
    int float_IST = ceil((IST - int_IST) * 60);
 
    cout << int_IST << ":" << float_IST;
}
 
// Driver code
int main()
{
 
    // Number of hours (1 - 24)
    int h = 20;
 
    // Rotations in degrees
    float r = 150;
 
    cal_IST(h, r);
 
    return 0;
}

Java




// Java implementation of the approach
import java.math.*;
 
class GFG
{
    // Function to calculate Indian Standard Time
    public static void cal_IST(int h, double r)
    {
        double IST = (h * r * 1.0) / 360;
 
        // Separate integer part
        int int_IST = (int)IST;
 
        // Separate float part and return ceil value
        int float_IST = (int)Math.ceil((int)((IST - int_IST) * 60));
 
        System.out.println(int_IST + ":" + float_IST);
    }
 
    // Driver code
    public static void main(String[] args)
    {
     
        // Number of hours (1 - 24)
        int h = 20;
     
        // Rotations in degrees
        double r = 150;
     
        cal_IST(h, r);
    }
}
 
// This code is contributed by Naman_Garg

Python3




# Python3 implementation of the approach
from math import ceil
 
# Function to calculate Indian Standard Time
def cal_IST(h, r) :
 
    IST = round((h * r * 1.0) / 360, 3);
 
    # Separate integer part
    int_IST = int(IST);
 
    # Separate float part and return ceil value
    float_IST = ceil((IST - int_IST) * 60);
 
    print(int_IST, ":", float_IST);
 
# Driver code
if __name__ == "__main__" :
 
    # Number of hours (1 - 24)
    h = 20;
 
    # Rotations in degrees
    r = 150;
 
    cal_IST(h, r);
 
# This code is contributed by AnkitRai01

C#




// C# implementation of the approach
using System;
 
class GFG
{
    // Function to calculate Indian Standard Time
    public static void cal_IST(int h, double r)
    {
        double IST = (h * r * 1.0) / 360;
 
        // Separate integer part
        int int_IST = (int)IST;
 
        // Separate float part and return ceil value
        int float_IST = (int)Math.Floor((
                         double)(IST - int_IST) * 60);
 
        Console.WriteLine(int_IST + ":" + float_IST);
    }
 
    // Driver code
    public static void Main(String[] args)
    {
     
        // Number of hours (1 - 24)
        int h = 20;
     
        // Rotations in degrees
        double r = 150;
     
        cal_IST(h, r);
    }
}
 
// This code is contributed by PrinciRaj1992

Javascript




<script>
// Javascript implementation of the approach
 
// Function to calculate Indian Standard Time
function cal_IST(h, r)
{
    let IST = (h * r * 1.0) / 360;
 
    // Separate integer part
    let int_IST = parseInt(IST);
 
    // Separate float part and return ceil value
    let float_IST = Math.ceil(parseInt((IST - int_IST) * 60));
 
    document.write(int_IST + ":" + float_IST);
}
 
// Driver code
 
    // Number of hours (1 - 24)
    let h = 20;
 
    // Rotations in degrees
    let r = 150;
 
    cal_IST(h, r);
 
// This code is contributed by subhammahato348.
</script>
Output: 
8:20

 

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