add brute force solution for 0001-two-sum (#85)

* add brute force solution for 0001-two-sum

* go fmt

Author: zwfang

go.mod

@@ -1,3 +1,3 @@
 module leetcode
 
-go 1.12
+go 1.13

src/0001_two_sum/twosum.go

@@ -32,3 +32,17 @@ func twoSum(nums []int, target int) []int {
 	}
 	return []int{}
 }
+
+// brute force
+// Time complexity: O(n^2)
+// Space complexity: O(1)
+func twoSum1(nums []int, target int) []int {
+	for i, j := range nums {
+		for k := i + 1; k < len(nums); k++ {
+			if nums[k]+j == target {
+				return []int{i, k}
+			}
+		}
+	}
+	return []int{}
+}

src/0001_two_sum/twosum_test.go

@@ -8,11 +8,15 @@ import (
 func TestTwoSum(t *testing.T) {
 	nums := []int{2, 7, 11, 15}
 
-	if res := twoSum(nums, 9); !reflect.DeepEqual(res, []int{0, 1}) {
-		t.Error("Failed, two sum")
-	}
+	funcs := []func([]int, int) []int{twoSum, twoSum1}
+
+	for _, testFunc := range funcs {
+		if res := testFunc(nums, 9); !reflect.DeepEqual(res, []int{0, 1}) {
+			t.Error("Failed, two sum")
+		}
 
-	if res := twoSum(nums, 6); !reflect.DeepEqual(res, []int{}) {
-		t.Error("Failed, two sum")
+		if res := testFunc(nums, 6); !reflect.DeepEqual(res, []int{}) {
+			t.Error("Failed, two sum")
+		}
 	}
 }

src/0713_subarray_product_less_than_k/spltk_test.go

@@ -12,7 +12,7 @@ func TestNumSubArrayProductLessThanK(t *testing.T) {
 	ks := []int{100, 0, 100}
 	expected := []int{8, 0, 4}
 
-	functions := []func([]int, int)int{
+	functions := []func([]int, int) int{
 		numSubArrayProductLessThanK,
 		numSubArrayProductLessThanK2,
 	}