fix readme and add test

Author: ongch

LeetcodeProblems/Algorithms/2Sum.js

@@ -32,7 +32,7 @@ Output: [0,1]
   let map ={};
   for(let i=0;i<nums.length;i++){
       const sum = target-nums[i];
-      if(map[parseInt(sum)] != void 0){
+      if(map[parseInt(sum)] != 0){
           return [map[sum], i];
       } else{
           map[nums[i]] = i;

LeetcodeProblemsTests/Algorithms/2Sum_Test.js

@@ -0,0 +1,11 @@
+const assert = require('assert');
+const twoSum = require('../../LeetcodeProblems/Algorithms/2Sum').twoSum;
+
+var test = function () {
+  assert.deepEqual([0,1], twoSum([2,7,11,15], 9));
+  assert.deepEqual([1,2], twoSum([3,2,4], 6));
+  assert.deepEqual([0,1], twoSum([3,3], 6));
+}
+
+module.exports.test = test;
+

README.md

@@ -78,7 +78,7 @@ To run a specific problem in your console run  `node <problem_file_path>` (e.g.
 | [Binary Gap ](/LeetcodeProblems/Algorithms/Binary_Gap.js)                                                       | Easy   | https://leetcode.com/problems/binary-gap/ |
 | [Binary Gap ](/LeetcodeProblems/Algorithms/Binary_Gap.js)                                                       | Easy   | https://leetcode.com/problems/binary-gap/ |
 | [Majority Element](/LeetcodeProblems/Algorithms/Majority_Element.js)                                            | Easy   | https://leetcode.com/problems/majority-element/ |
-| [Two Sum](/LeetcodeProblems/Algorithms/2Sum.js)                                            | Easy   | https://leetcode.com/problems/two-sum/ |
+| [Two Sum](/LeetcodeProblems/Algorithms/2Sum.js)                                                                 | Easy   | https://leetcode.com/problems/two-sum/ |
 | [Tic Tac Toe ](/LeetcodeProblems/Algorithms/Tic_Tac_Toe.js)                                                     |        | |
 | [Permutations With Duplicates ](/LeetcodeProblems/Algorithms/Permutations_With_Duplicates.js)                   |        | |
 | [Deletion Distance](/LeetcodeProblems/Algorithms/Deletion_Distance.js)                                          |        | |