Compare Version Numbers

JINGUIWANG · JINGUIWANG · commit de27c6abb0aa · 2014-12-17T20:07:39.000+08:00
Change-Id: I9c03f888e46db11757f4c8e8f14b29dbd9505f09
diff --git a/CompareVersionNumbers.h b/CompareVersionNumbers.h
@@ -0,0 +1,40 @@
+/*
+ Author:     King, wangjingui@outlook.com
+ Date:       Dec 15, 2014
+ Problem:    Compare Version Numbers
+ Difficulty: Easy
+ Source:     https://oj.leetcode.com/problems/compare-version-numbers/
+ Notes:
+ 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
+
+ Solution: ...
+ */
+class Solution {
+public:
+    int compareVersion(string version1, string version2) {
+        int v1len = version1.size(), v2len = version2.size();
+        for (int i = 0, j = 0; (i < v1len || j < v2len); ) {
+        	long long a = 0, b =0;
+        	while (i < v1len && version1[i] != '.') {
+        		a = a * 10 + version1[i++] - '0';
+        	}
+        	++i;
+        	while (j < v2len && version2[j] != '.') {
+        		b = b * 10 + version2[j++] - '0';
+        	}
+        	++j;
+        	if (a > b) return 1;
+        	if (a < b) return -1;
+        }
+    	return 0;
+    }
+};
