Leetcode题目：Compare Version Numbers

题目：

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

题目解答：

　　题目要求对输入的两个版本号，比较其大小。

　　思路：（1）将版本号按照.号分隔。得到字符串向量。

　　　　　（2）将字符串转成整数值比较大小。

　　需要注意的是几个特殊的例子需要考虑： 1.0.0 vs 1 这个结果应该是相等的。

代码：

class Solution {
public:
    int compareVersion(string version1, string version2) {
        if((version1 == "") || (version2 == ""))
            return 0;
        vector<int> v1_vec = getVersionNum(version1);
        vector<int> v2_vec = getVersionNum(version2);
        auto vit1 = v1_vec.begin();
        auto vit2 = v2_vec.begin();
        while((vit1 != v1_vec.end()) && (vit2 != v2_vec.end() ) )
        {
            if(*vit1 < *vit2)
            {
                return -1;
            }
            else if(*vit1 > *vit2)
            {
                return 1;
            }
            else
            {
                vit1++;
                vit2++;
            }
        }
        if( (vit1 == v1_vec.end()) && (vit2 != v2_vec.end()) )
        {
            int leave = 0;
            while(vit2 != v2_vec.end() )
            {
                leave += *vit2;
                vit2++;
            }
            if(leave > 0)
                return -1;
            else
                return 0;
        }
        else if( (vit1 != v1_vec.end()) && (vit2 == v2_vec.end() ))
        {
            int leave = 0;
            while(vit1 != v1_vec.end() )
            {
                leave += *vit1;
                vit1++;
            }
            if(leave > 0)
                return 1;
            else
                return 0;
        }
        else
            return 0;
        
    }
    
    
    vector<int> getVersionNum(string s)
    {
        vector<int> res;
        vector<string> sve = stringSplit(s);
        for(auto sit = sve.begin(); sit != sve.end(); sit++)
        {
            
            int num_tmp = 0;
            num_tmp = atoi((*sit).c_str());
            cout << num_tmp << endl;
            res.push_back(num_tmp);
        }
        return res;
    }
    
    
    
    vector<string> stringSplit(string s)
    {
        vector<string> res;
        string::iterator sit = s.begin();
        string tmp;
        tmp.clear();
        while(sit != s.end())
        {
            if(*sit == '.')
            {
                res.push_back(tmp);
                tmp.clear();
            }
            else
            {
                tmp += *sit; 
            }
            sit++;
        }
        res.push_back(tmp);
       // cout << tmp << endl;
        tmp.clear();
        return res;
    }
};