Compare Version Numbers

Desicription

Compare two version numbers version1 and version2.
If version1 > version2 return 1; if version1 < version2 return -1;otherwise return 0.

You may assume that the version strings are non-empty and contain only digits and the . character.
The . character does not represent a decimal point and is used to separate number sequences.
For instance, 2.5 is not “two and a half” or “half way to version three”, it is the fifth second-level revision of the second first-level revision.

Example 1:

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Input: version1 = "0.1", version2 = "1.1"
Output: -1

Example 2:

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Input: version1 = "1.0.1", version2 = "1"
Output: 1

Example 3:

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Input: version1 = "7.5.2.4", version2 = "7.5.3"
Output: -1

Solution

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class Solution {
public:
int compareVersion(string version1, string version2) {
int num1 = 0;
int num2 = 0;
int n1 = version1.size();
int n2 = version2.size();
int i = 0;
int j = 0;
while(i < n1 || j < n2) {
while(i < n1 && version1[i] != '.')
num1 = num1 * 10 + version1[i++] - '0';
while(j < n2 && version2[j] != '.')
num2 = num2 * 10 + version2[j++] - '0';
if(num1 > num2)
return 1;
else if(num1 < num2)
return -1;
num1 = 0;
num2= 0;
i++;
j++;
}
return 0;
}
};