Compare Version Numbers

题目：leetcode

  

Compare two version numbers version1 and version1.
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

vector<int> getnum(const string &version){vector<int> res;int pre = 0;for (int i = 0; i < version.size(); i++){if (version[i] == '.'){string str(version.begin() + pre, version.begin() + i);res.push_back(stoi(str));pre = i + 1;}}string str(version.begin() + pre, version.end());res.push_back(stoi(str));return res;}int compare_version(const string &version1, const string &version2){if (version1.empty() || version2.empty())throw exception();int count1 = 0, count2 = 0;for (int i = 0; i<version1.size(); i++){if (version1[i] == '.')count1++;}for (int i = 0; i<version2.size(); i++){if (version2[i] == '.')count2++;}if (count1>count2)return -1 * compare_version(version2, version1);vector<int> num1 = getnum(version1);vector<int> num2 = getnum(version2);int index = 0;while (index < num1.size()){if (num1[index] == num2[index])index++;elsebreak;}if (index == num1.size()){if (num1.size() == num2.size())return 0;//注意version2后面全是零的情况！！while (index < num2.size()){if (num2[index] != 0)return -1;index++;}//注意version2后面全是零的情况！！如 1.2 与 1.2.0.0.0return 0;}else{if (num1[index] > num2[index])return 1;else if (num1[index] < num2[index])return -1;elsereturn 0;}}