165. 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.
You may assume the default revision number for each level of a version number to be 0. For example, version number 3.4 has a revision number of 3 and 4 for its first and second level revision number. Its third and fourth level revision number are both 0.
Example 1:
Input: version1 = "0.1", version2 = "1.1" Output: -1
Example 2:
Input: version1 = "1.0.1", version2 = "1" Output: 1
Example 3:
Input: version1 = "7.5.2.4", version2 = "7.5.3" Output: -1
Example 4:
Input: version1 = "1.01", version2 = "1.001" Output: 0 Explanation: Ignoring leading zeroes, both “01” and “001" represent the same number “1”
Example 5:
Input: version1 = "1.0", version2 = "1.0.0" Output: 0 Explanation: The first version number does not have a third level revision number, which means its third level revision number is default to "0"
Note:
Version strings are composed of numeric strings separated by dots . and this numeric strings may have leading zeroes. Version strings do not start or end with dots, and they will not be two consecutive dots.
難度：medium
題目：比較兩個版本version1和version2.
如果1大於2返回1,1小於2返回－1，否則返回0.假定版本字串中非空且只含有數字和點。點不是小數點只是用作分隔符。
思路：按點號分割轉成數字比較。
Runtime: 1 ms, faster than 89.87% of Java online submissions for Compare Version Numbers.
Memory Usage: 33.1 MB, less than 100.00% of Java online submissions for Compare Version Numbers.
class Solution {
public int compareVersion(String version1, String version2) {
String[] vs1 = version1.split("\\.");
String[] vs2 = version2.split("\\.");
for (int i = 0; i < Math.max(vs1.length, vs2.length); i++) {
int i1 = i < vs1.length ? Integer.parseInt(vs1[i]) : 0;
int i2 = i < vs2.length ? Integer.parseInt(vs2[i]) : 0;
if (i1 - i2 > 0) {
return 1;
}
if (i1 - i2 < 0) {
return -1;
}
}
return 0;
}
}