leetcode 165

165. Compare Version Numbers

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.

Here is an example of version numbers ordering:

0.1 < 1.1 < 1.2 < 13.37

比较版本号，版本号由数字和‘.’组成，且为string类型。
思路：忽略‘.’将字符串的每位依次转换为数字，然后比较大小。
代码如下：

class Solution {
public:
    int compareVersion(string version1, string version2) {
        int temp1;
        int temp2;
        int i = 0;
        int j = 0;
        while (i < version1.length() || j < version2.length()) 
        {
            temp1 = 0;
            temp2 = 0;
            //
            while (i < version1.length() && '.' != version1[i])
            {
                temp1 = temp1 * 10 + (version1[i] - '0');
                i++;
            }
            i++;
            //
            while (j < version2.length() && '.' != version2[j]) 
            {
                temp2 = temp2 * 10 + (version2[j] - '0');
                j++;
            }
            j++;
            if (temp1 > temp2) 
            {
                return 1;
            }
            if (temp1 < temp2) 
            {
                return -1;
            }
        }
        return 0;
    }
};