Merge pull request neetcode-gh#52 from ArwaNayef/patch-2

Create 15-3Sum

Author: neetcode-gh

java/15-3Sum

@@ -0,0 +1,39 @@
+class Solution {
+//2 pointers
+    public List<List<Integer>> threeSum(int[] nums) {
+        Arrays.sort(nums);
+        LinkedList<List<Integer>> sol = new LinkedList<List<Integer>>();
+
+        for (int i = 0; i < nums.length - 2; i++) {
+            if (i == 0 || (i > 0 && nums[i] != nums[i - 1])) {
+                int target = 0 - nums[i];
+                int left = i + 1;
+                int right = nums.length - 1;
+
+                while (left < right) {
+                    if (nums[left] + nums[right] == target) {
+                        ArrayList<Integer> miniSol = new ArrayList<>();
+                        miniSol.add(nums[i]);
+                        miniSol.add(nums[left]);
+                        miniSol.add(nums[right]);
+                        sol.add(miniSol);
+                        while (left < right && nums[left] == nums[left + 1]) {
+                            left++;
+                        }
+                        while (left < right && nums[right] == nums[right - 1]) {
+                            right--;
+                        }
+                        left++;
+                        right--;
+                    } else if (nums[left] + nums[right] > target) {
+                        right--;
+                    } else {
+                        left++;
+                    }
+                }
+            }
+        }
+
+        return sol;
+    }
+}