Difference between two given times

Given two times in string “HH:MM” format. Here ‘H’ shows hours and ‘M’ shows minutes. You have to find the difference in the same string format between these two strings. But both given strings should follow these cases. 
1) Time 1 will be less than or equal to time2 
2) Hours will be possible from 0 to 23. 
3) Minutes will be possible from 0 to 59

Examples: 

Input : s1 = "14:00";
        s2 = "16:45";
Output : result = "2:45"

Input : s1 = "1:04"
        s2 = "13:05"
Output : result = "12:01"

The idea is to first remove colon. After removing colon, hour difference can be computed using simple mathematics. 

C++

// C++ program to find difference between two
// given times.
#include <bits/stdc++.h>
using namespace std;

// remove ':' and convert it into an integer
int removeColon(string s)
{
    if (s.size() == 4)
        s.replace(1, 1, "");

    if (s.size() == 5)
        s.replace(2, 1, "");

    return stoi(s);
}

// Main function which finds difference
string diff(string s1, string s2)
{

    // change string (eg. 2:21 --> 221, 00:23 --> 23)
    int time1 = removeColon(s1);
    int time2 = removeColon(s2);

    // difference between hours
    int hourDiff = time2 / 100 - time1 / 100 - 1;

    // difference between minutes
    int minDiff = time2 % 100 + (60 - time1 % 100);

    if (minDiff >= 60) {
        hourDiff++;
        minDiff = minDiff - 60;
    }

    // convert answer again in string with ':'

    string res = to_string(hourDiff) + ':' + to_string(minDiff);
    return res;
}

// Driver program to test above functions
int main()
{
    string s1 = "14:00";
    string s2 = "16:45";
    cout << diff(s1, s2) << endl;
    return 0;
}

Java

/*package whatever //do not write package name here */
import java.io.*;

class GFG
{

    // Java program to find difference between two
// given times.

// remove ':' and convert it into an integer
static int removeColon(String s)
{
    if (s.length() == 4)
        s = s.substring(0,1) + s.substring(2);

    if (s.length() == 5)
        s = s.substring(0,2) + s.substring(3);

    return Integer.valueOf(s);
}

// Main function which finds difference
static String diff(String s1, String s2)
{

    // change string (eg. 2:21 --> 221, 00:23 --> 23)
    int time1 = removeColon(s1);
    int time2 = removeColon(s2);

    // difference between hours
    int hourDiff = time2 / 100 - time1 / 100 - 1;

    // difference between minutes
    int minDiff = time2 % 100 + (60 - time1 % 100);

    if (minDiff >= 60) {
        hourDiff++;
        minDiff = minDiff - 60;
    }

    // convert answer again in string with ':'

    String res = String.valueOf(hourDiff) + ':' + String.valueOf(minDiff);
    return res;
}

// Driver Code
public static void main(String args[])
{
    String s1 = "14:00";
    String s2 = "16:45";
    System.out.println(diff(s1, s2));
}
}

// This code is contributed by shinjanpatra

Python3

# Python 3 program to find difference between two
# given times.

# Remove ':' and convert it into an integer
def removeColon(s):

    if (len(s) == 4):
        s = s[:1] + s[2:]

    if (len(s) == 5):
        s = s[:2] + s[3:]

    return int(s)

# Main function which finds difference
def diff(s1, s2):

    # Change string
    # (eg. 2:21 --> 221, 00:23 --> 23)
    time1 = removeColon(s1)
    time2 = removeColon(s2)

    # Difference between hours
    hourDiff = time2 // 100 - time1 // 100 - 1;

    # Difference between minutes
    minDiff = time2 % 100 + (60 - time1 % 100)

    if (minDiff >= 60):
        hourDiff += 1
        minDiff = minDiff - 60

    # Convert answer again in string with ':'
    res = str(hourDiff) + ':' + str(minDiff)

    return res

# Driver code
s1 = "14:00"
s2 = "16:45"

print(diff(s1, s2))

# This code is contributed by ApurvaRaj

C#

// C# program to find difference between two
// given times.

using System;

class GFG {

    // remove ':' and convert it into an integer
    static int removeColon(string s)
    {
        if (s.Length == 4)
            s = s.Substring(0, 1) + s.Substring(2);

        if (s.Length == 5)
            s = s.Substring(0, 2) + s.Substring(3);

        return Convert.ToInt32(s);
    }

    // Main function which finds difference
    static string diff(string s1, string s2)
    {

        // change string (eg. 2:21 --> 221, 00:23 --> 23)
        int time1 = removeColon(s1);
        int time2 = removeColon(s2);

        // difference between hours
        int hourDiff = time2 / 100 - time1 / 100 - 1;

        // difference between minutes
        int minDiff = time2 % 100 + (60 - time1 % 100);

        if (minDiff >= 60) {
            hourDiff++;
            minDiff = minDiff - 60;
        }

        // convert answer again in string with ':'

        string res = Convert.ToString(hourDiff) + ":"
                     + Convert.ToString(minDiff);
        return res;
    }

    // Driver Code
    public static void Main(string[] args)
    {
        string s1 = "14:00";
        string s2 = "16:45";
        Console.WriteLine(diff(s1, s2));
    }
}

// This code is contributed by phasing17

Javascript

<script>
// JavaScript program to find difference between two
// given times.

// remove ':' and convert it into an integer
function removeColon( s)
{
    if (s.length == 4)
        s= s.replace(":", "");

    if (s.length == 5)
        s= s.replace(":", "");

    return parseInt(s);
}

// Main function which finds difference
function diff( s1,  s2)
{

    // change string (eg. 2:21 --> 221, 00:23 --> 23)
     time1 = removeColon(s1);

     time2 = removeColon(s2);


    // difference between hours
     hourDiff = parseInt(time2 / 100 - time1 / 100 - 1);

    // difference between minutes
     minDiff = parseInt(time2 % 100 + (60 - time1 % 100));

    if (minDiff >= 60) {
        hourDiff++;
        minDiff = minDiff - 60;
    }

    // convert answer again in string with ':'
    res = (hourDiff).toString() + ':' + (minDiff).toString();
    return res;
}

// Driver program to test above functions
    s1 = "14:00";
    s2 = "16:45";
    console.log(diff(s1, s2));

// This code is contributed by ukasp.
</script>

Output: 

2:45

Time complexity: O(1), as the length of the string will be either 4 or 5, the operations performed by stoi and replace will be considered to be constant.
Auxiliary space: O(1)

This article is contributed by Harshit Agrawal. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.