Added 3 Sum Closest

Author: ignacio-chiazzo

.gitignore

@@ -1,4 +1,6 @@
 tips
 .DS_Store
 
-node_modules/
+node_modules/
+
+JAVASCRIPT.md

LeetcodeProblems/Algorithms/3SumClosest.js

@@ -0,0 +1,63 @@
+/*
+3Sum Closest
+https://leetcode.com/problems/3sum-closest/
+
+Given an integer array nums of length n and an integer target, find three integers in nums such that the sum is closest to target.
+
+Return the sum of the three integers.
+
+You may assume that each input would have exactly one solution.
+
+Example 1:
+
+Input: nums = [-1,2,1,-4], target = 1
+Output: 2
+Explanation: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
+Example 2:
+
+Input: nums = [0,0,0], target = 1
+Output: 0
+ 
+
+Constraints:
+
+3 <= nums.length <= 1000
+-1000 <= nums[i] <= 1000
+-104 <= target <= 104
+*/
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
+ var threeSumClosest = function(nums, target) {
+  let mid = 1;
+  let right = nums.length - 1;
+  let currentSum = nums[0] + nums[mid] + nums[right];
+  let closest = currentSum;
+  
+  nums.sort(function(a,b) {return a - b})
+  
+  for(var left = 0 ; left < nums.length - 1; left++) {
+      mid = left + 1;
+      right = nums.length - 1;
+      
+      while(mid < right) {
+          currentSum = nums[left] + nums[mid] + nums[right];
+          
+          if(Math.abs(target - currentSum) < Math.abs(target - closest)) {
+              closest = currentSum;
+          }
+          
+          if(currentSum > target) {
+              right--;
+          } else {
+              mid++;
+          }
+      }
+  }
+  
+  return closest;
+};
+
+module.exports.threeSumClosest = threeSumClosest;

LeetcodeProblemsTests/Algorithms/3Sum_Closest_Test.js

@@ -0,0 +1,10 @@
+const assert = require('assert');
+const threeSumClosest = require('../../LeetcodeProblems/Algorithms/3SumClosest').threeSumClosest;
+
+var test = function () {
+  assert.equal(2, threeSumClosest([-1, 2 , 1, -4], 1));
+  assert.equal(0, threeSumClosest([0, 0, 0], 1));
+  
+}
+
+module.exports.test = test;

README.md

@@ -23,6 +23,7 @@ To run a specific problem in your console run  `node <problem_file_path>` (e.g.
 | [merge k sorted lists ](/LeetcodeProblems/Algorithms/merge_k_sorted_lists.js)                                   | Hard   | https://leetcode.com/problems/merge-k-sorted-lists/ |
 | [Set Matrix Zeroes](/LeetcodeProblems/Algorithms/Set_Matrix_Zeroes.js)                                          | Hard   | https://leetcode.com/problems/set-matrix-zeroes/ |
 | [Subarray Sum Equals K ](/LeetcodeProblems/Algorithms/Subarray_Sum_Equals_K.js)                                 | Medium | https://leetcode.com/problems/subarray-sum-equals-k/ | 
+| [3Sum Closest](/LeetcodeProblems/Algorithms/3SumClosest.js)                                                     | Medium | https://leetcode.com/problems/3sum-closest/ | 
 | [3Sum ](/LeetcodeProblems/Algorithms/3Sum.js)                                                                   | Medium | https://leetcode.com/problems/3sum/ | 
 | [NumberOfIslands ](/LeetcodeProblems/Algorithms/Number_of_Islands.js)                                           | Medium | https://leetcode.com/problems/number-of-islands/ | 
 | [Swap Nodes in Pairs](/LeetcodeProblems/Algorithms/Swap_Nodes_in_Pairs.js)                                      | Medium | https://leetcode.com/problems/swap-nodes-in-pairs/ |