## [LeetCode]Compare Version Numbers

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`

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

```class Solution {
public:
int compareVersion(string version1, string version2) {
string leftVersion1 = version1;
string leftVersion2 = version2;
while(leftVersion1!=""&&leftVersion2!=""){
int subver1, subver2;

int pos1 = leftVersion1.find('.');
if(pos1!=string::npos){
subver1 = strToInt(leftVersion1.substr(0, pos1));
leftVersion1 = leftVersion1.substr(pos1 + 1);
}else{
subver1 = strToInt(leftVersion1);
leftVersion1 = "";
}

int pos2 = leftVersion2.find('.');
if(pos2!=string::npos){
subver2 = strToInt(leftVersion2.substr(0, pos2));
leftVersion2 = leftVersion2.substr(pos2 + 1);
}else{
subver2 = strToInt(leftVersion2);
leftVersion2 = "";
}

if(subver1>subver2){
return 1;
}
if(subver1<subver2){
return -1;
}
}
if(leftVersion1!=""&&!checkAllZero(leftVersion1)){
return 1;
}
if(leftVersion2!=""&&!checkAllZero(leftVersion2)){
return -1;
}
return 0;
}
private:
int strToInt(string s){
int base = 1;
int result = 0;
int len = s.length();
for(int i=len-1;i>=0; i--){
result += base*(s[i]-'0');
base *= 10;
}
return result;
}
bool checkAllZero(string s){
int len = s.length();
for(int i = 0; i<len; i++){
if(s[i]!='.' && s[i]!='0'){
return false;
}
}
return true;
}
};```

```class Solution {
public:
int compareVersion(string version1, string version2) {
while(version1!=""&&version2!=""){
int pos1 = version1.find('.');
int pos2 = version2.find('.');
int subversion1, subversion2;
if(pos1<0){
subversion1 = atoi(version1.c_str());
version1 = "";
}else{
string s1 = version1.substr(0, pos1);
subversion1 = atoi(s1.c_str());
version1 = version1.substr(pos1 + 1);
}
if(pos2<0){
subversion2 = atoi(version2.c_str());
version2 = "";
}else{
string s2 = version2.substr(0, pos2);
subversion2 = atoi(s2.c_str());
version2 = version2.substr(pos2 + 1);
}
if(subversion1<subversion2){
return -1;
}else if(subversion1>subversion2){
return 1;
}
}
if(version1!=""&&!checkAllZero(version1)){
return 1;
}
if(version2!=""&&!checkAllZero(version2)){
return -1;
}
return 0;
}

bool checkAllZero(string s){
int len = s.length();
for(int i = 0; i<len; i++){
if(s[i]!='.' && s[i]!='0'){
return false;
}
}
return true;
}
};```