Leetcode 165 Compare Version Numbers

题意：比较版本号的大小

有点变态，容易犯错

本质是字符串的比较，请注意他的版本号的小数点不知1个，有的会出现01.0.01这样的变态版本号

class Solution {
public:
    int cmp_num(string a, string b){
        if(a.size() < b.size()) return -;
        else if(a.size() == b.size()){
            if(a == b) return ;
            else return a < b ? -: ;
        }
        else return ;
    }
    vector<string> change(string v){
        vector<string> vs;
        int a = , b = ;
        while((b = v.find(".",a)) != string::npos){
            string::size_type i = a;
            for(; i < v.size(); ++i){
                if(v[i] > '' || v[i] == '.') break;
            }
            if(i == v.size() || v[i] == '.') vs.push_back("");
            else vs.push_back(v.substr(i, b- i));
            a = b + ;
        }
        string::size_type i = a;
        for(; i < v.size(); ++i){
            if(v[i] > '' || v[i] == '.') break;
        }
        if(i == v.size() || v[i] == '.') vs.push_back("");
        else vs.push_back(v.substr(i,  v.size() - i));
        return vs;
    }
    int compareVersion(string version1, string version2) {
        vector<string> v1,v2;
        v1 = change(version1);
        v2 = change(version2);

        string::size_type i;
        for(i = ; i < v1.size() && i <v2.size(); ++i){
            if(cmp_num(v1[i],v2[i]) != ) return cmp_num(v1[i],v2[i]);
        }

        for(; i < v1.size(); ++i){
            if(cmp_num(v1[i],"") != ) return cmp_num(v1[i],"");
        }

        for(; i < v2.size(); ++i){
            if(cmp_num("",v2[i]) != ) return cmp_num("",v2[i]);
        }

        return ;
    }
};