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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 ``#include ``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

 ``
Output:
`8:20`

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