add two sum and test

Author: XianCH

Diff for: 0001_two_sum.go

@@ -0,0 +1,18 @@
+package leetcode
+
+func Twonum(nums []int, target int) []int {
+	m := make(map[int]int)
+	for i := 0; i < len(nums); i++ {
+		another := target - nums[i]
+		if _, ok := m[another]; ok {
+			return []int{m[another], i}
+		}
+		m[nums[i]] = i
+	}
+	return nil
+}
+
+// Given nums = [2, 7, 11, 15], target = 9,
+//
+// Because nums[0] + nums[1] = 2 + 7 = 9,
+// return [0, 1]

Diff for: 0001_two_sum_test.go

@@ -0,0 +1,25 @@
+package leetcode
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestTwonum(t *testing.T) {
+	tests := []struct {
+		nums   []int
+		target int
+		want   []int
+	}{
+		{[]int{2, 7, 6, 2}, 9, []int{0, 1}},
+		{[]int{3, 2, 4}, 6, []int{1, 2}},
+		{[]int{3, 3}, 6, []int{0, 1}},
+	}
+
+	for _, tt := range tests {
+		got := Twonum(tt.nums, tt.target)
+		if !reflect.DeepEqual(got, tt.want) {
+			t.Errorf("Twonum(%v,%d)=%v,want %v", tt.nums, tt.target, got, tt.want)
+		}
+	}
+}