ad PR guide

lessfish · lessfish · commit 3a85fd03e3e9 · 2017-10-08T22:08:27.000+08:00
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -0,0 +1,9 @@
+# CONTRIBUTING 
+
+It's a personal project for leetcode solutions, but PRs welcomed as well.
+
+You should meet the following conditions:
+
+- the question of the solution you submit should have been solved by me 
+- you should have a better solution either in time complexity or space complexity
+- you should use JavaScript or Python
diff --git a/readme.md b/readme.md
@@ -1,6 +1,6 @@
-# Leetcode Solutions with JavaScript
+# Leetcode Solutions with JavaScript [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md)
 
-Update time: Sun Oct 08 2017 21:38:27 GMT+0800 (CST)
+Update time: Sun Oct 08 2017 21:45:17 GMT+0800 (CST)
 
 I have solved **344 / 618** problems while **114** problems are still locked.
 
