version1 and version2.
If version1 > version2 return 1, if version1 < version2

​​.​​ character.

The ​​.​​ character does not represent a decimal point and is used to separate number sequences.

For instance, ​​2.5​​

0.1 < 1.1 < 1.2 < 13.37

注意getline这种分割字符串的能力！

class Solution {
public:
  int compareVersion(string version1, string version2) {
    stringstream ss1(version1);
    stringstream ss2(version2);
    while (!ss1.eof() || !ss2.eof()){//||
      string v1="0", v2="0";//"0"
      getline(ss1, v1, '.');
      getline(ss2, v2, '.');
      int nv1 = stoi(v1);
      int nv2 = stoi(v2);
      if (nv1 < nv2){
        return -1;
      }
      else if (nv1>nv2){
        return 1;
      }
    }
    return 0;
  }
};