Last Updated: 30 Dec, 2020
Compare Version Numbers
Easy
Asked in companies
You are given two versions numbers A and B as a string. Your task is to compare them and find out which one of them is a newer version.
Note:
There are no leading zeros in any of the strings except in the case of zero itself. Note that, the leading zeroes are not allowed even after a '.' ie: 121.005 is an invalid version, while 121.5 is an valid version.
For Example:
A = “1.23.45”, B = “1.23.456”
The first two parts of both the strings are the same i.e 1 and 23 and the third part of B is greater than the third part of A i.e. 45 < 456, thus string B is the latest version.
Input format:
The first line contains an integer 'T' which denotes the number of test cases or queries to be run. Then, the T test cases follow.
The first line of each test case contains version A as a string.
The second line of each test case contains version B as a string.
Output format:
For each test case, print 1 if version A is latest, -1 if version B is latest and 0 if both versions are the same.
Note:
You do not need to print anything; it has already been taken care of. Just implement the given functions.
Constraints:
1 <= T <= 10
1 <= |A|, |B| <= 10^5
All the string A and B characters contain digits and dots only and both the strings are started and terminated by a digit.
Approaches
First of all, we will delete the zeros from the end of both the strings. For example: Convert 1.0.0 to 1, and 2.2.0 to 2.2 etc.
Now, the idea is to use an iterative approach to compare both strings.
We will use four-pointers start1,end1 (pointing to version A) and start2,end2 (pointing to version B) all initialized to 0. We will move end1 to the first dot to the right of start1 ( or the end of the string if no such dot exists) and we will move end2 to the first dot to the right of start2 ( or the end of the string if no such dot exists) now If :
- end1 > end2
- Version A is the latest
- end2 > end1
- Version B is the latest
- end2 = end1
- In this case, we will compare both the strings from their respective start points and endpoints and output the result of the comparison. If both the strings are equal we will move start1 to end1 and start2 to end2 and will do the same process iteratively.
If we reach the end of both the strings without terminating this means that both the strings are equal and we will return 0 in this case.