compare version numbers

fishercoder1534 · fishercoder1534 · commit 7459736da5a4 · 2016-10-28T15:21:10.000-07:00
diff --git a/EASY/src/easy/CompareVersionNumbers.java b/EASY/src/easy/CompareVersionNumbers.java
@@ -0,0 +1,43 @@
+package easy;
+
+public class CompareVersionNumbers {
+
+    public static int compareVersion(String version1, String version2) {
+        String[] v1s = version1.split("\\.");//escaping it is very important! Otherwise, it's not going to work as expected!
+        String[] v2s = version2.split("\\.");
+        int len = (v1s.length < v2s.length) ? v2s.length : v1s.length;
+        for(int i = 0; i < len; i++){
+            if(v1s.length == i){
+                while(i < len){
+                    if(Integer.parseInt(v2s[i]) > 0) return -1;
+                    i++;
+                }
+            } else if(v2s.length == i){
+                while(i < len){
+                    if(Integer.parseInt(v1s[i]) > 0) return 1;
+                    i++;
+                }
+            } else {
+                if(Integer.parseInt(v1s[i]) > Integer.parseInt(v2s[i])) return 1;
+                else if(Integer.parseInt(v2s[i]) > Integer.parseInt(v1s[i])) return -1;
+                else continue;//this line is not necessary, but just to make the logic more clear
+            }
+        }
+        return 0;
+    }
+    
+    public static void main(String...args){
+//        String version1 = "1.1";
+//        String version2 = "1.2";//should return -1
+        
+//        String version1 = "1.0.1";
+//        String version2 = "1";//should return 1
+        
+        String version1 = "1.0";
+        String version2 = "1";//should return 0
+        
+        /**"1.0.1", "1"*/
+        System.out.println(compareVersion(version1, version2));
+    }
+
+}
diff --git a/README.md b/README.md
@@ -32,6 +32,7 @@
 |189|[Rotate Array](https://leetcode.com/problems/rotate-array/)|[Solution](../../blob/master/EASY/src/easy/RotateArray.java)| O(n)|O(n), could be optimized to O(1) | Easy
 |173|[Binary Search Tree Iterator](https://leetcode.com/problems/binary-search-tree-iterator/)|[Queue](../../blob/master/MEDIUM/src/medium/BSTIterator_using_q.java) [Stack](../../blob/master/MEDIUM/src/medium/BSTIterator_using_stack.java)| O(1) |O(h) | Medium|
 |172|[Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes/)|[Solution](../../blob/master/EASY/src/easy/FactorialTrailingZeroes.java)| O(logn)|O(1)| Easy
+|165|[Compare Version Numbers](https://leetcode.com/problems/compare-version-numbers/)|[Solution](../../blob/master/EASY/src/easy/CompareVersionNumbers.java)| O(n)|O(1) | Easy|
 |162|[Find Peak Element](https://leetcode.com/problems/find-peak-element/)|[Solution](../../blob/master/MEDIUM/src/medium/FindPeakElement.java) | O(1) |O(logn)/O(n) | Binary Search|
 |155|[Min Stack](https://leetcode.com/problems/min-stack/)|[Solution](../../blob/master/EASY/src/easy/MinStack.java)| O(1)|O(n) | Easy| Stack
 |140|[Word Break II](https://leetcode.com/problems/word-break-ii/)|[Solution](../../blob/master/HARD/src/hard/WordBreakII.java)| ? |O(n^2) | Hard| Backtracking/DFS
