Add 15. 3SUm

Author: LuaanNguyen

README.md

@@ -26,6 +26,12 @@ If you only want to run tests in a specific problem `(e.g., ./easy/0001_two_sum)
 go test ./easy/0001_two_sum
 ```
 
+Clean test cache
+
+```bash
+go clean -testcache
+```
+
 ## Solutions (Continue Updating...)
 
 |                                                              Leetcode ID                                                              | Title & Solution                                                                                                            | Coefficient Of Difficulty |                                             Remarks                                              |                                                                                                        Approach                                                                                                        |

medium/15_3sum/15_3sum.go

@@ -0,0 +1,44 @@
+package three_sum
+
+import "sort"
+
+func ThreeSum(nums []int) [][]int {
+    res := make([][]int, 0)
+
+    //sort in asc 
+    sort.Slice(nums, func(i , j int) bool {
+        return nums[i] < nums[j]
+    })
+
+    for i := range nums {
+        if i > 0 && nums[i] == nums[i - 1] {
+            continue 
+        }
+
+        target := -nums[i]
+        j := i + 1 
+        k := len(nums) - 1
+
+        for j < k {
+            if target == nums[j] + nums[k] {
+                res = append(res, []int{nums[i], nums[j], nums[k]})
+
+                for j < k && nums[j] == nums[j + 1] {
+                    j++ 
+                }
+                for j < k  && nums[k] == nums[k - 1] {
+                    k--
+                }
+
+                j ++ 
+                k -- 
+            } else if target > nums[j] + nums[k] {
+                j ++ 
+            } else {
+                k --
+            }
+        }
+    }
+
+    return res
+}

medium/15_3sum/15_3sum_test.go

@@ -0,0 +1,39 @@
+package three_sum
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestThreeSum(t *testing.T) {
+	tests := []struct {
+		name 	string 
+		nums	[]int 
+		expectedResult 	[][]int
+	} {
+		{
+			name: "Test Case 1",
+			nums: []int{-1,0,1,2,-1,-4},
+			expectedResult: [][]int{{-1,-1,2}, {-1,0,1}},
+		},
+		{
+			name: "Test Case 2",
+			nums: []int{0,1,1},
+			expectedResult: [][]int{},
+		},
+		{
+			name: "Test Case 3",
+			nums: []int{0,0,0},
+			expectedResult: [][]int{{0,0,0}},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got := ThreeSum(test.nums) 
+			if !reflect.DeepEqual(got, test.expectedResult) {
+				t.Errorf("3Sum(%v) = %v, want = %v", test.nums, got, test.expectedResult)
+			}
+		})
+	}
+}