chore: added test case for zero sum triplets (#155)

Author: jaidensiu

array/zero_sum_triplets_test.go

@@ -23,6 +23,7 @@ func TestZeroSumTriplets(t *testing.T) {
 		{[]int{1, 2}, [][]int{}},
 		{[]int{1, 2, 3}, [][]int{}},
 		{[]int{1, -4, 3}, [][]int{{-4, 1, 3}}},
+		{[]int{0, 0, 0, 0}, [][]int{{0, 0, 0}}},
 		{[]int{1, 2, -4, 6, 3}, [][]int{{-4, 1, 3}}},
 		{[]int{-1, -2, -8, 6, 2, 3}, [][]int{{-8, 2, 6}, {-2, -1, 3}}},
 		{[]int{1, -2, -4, 5, -2, 4, 1, 3}, [][]int{{-4, 1, 3}, {-2, -2, 4}, {-2, 1, 1}}},