add leetcode 78

Author: lijinglin3

leetcode/0078.subsets/subsets.go

@@ -0,0 +1,29 @@
+package leetcode
+
+var ans [][]int
+
+func subsets(nums []int) [][]int {
+	ans = make([][]int, 0)
+
+	for i := 0; i <= len(nums); i++ {
+		cur := make([]int, 0, i)
+		backtrace(nums, 0, i, cur)
+	}
+
+	return ans
+}
+
+func backtrace(nums []int, pos, num int, cur []int) {
+	if len(cur) == num {
+		tmp := make([]int, len(cur))
+		copy(tmp, cur)
+		ans = append(ans, tmp)
+		return
+	}
+
+	for i := pos; i < len(nums); i++ {
+		cur = append(cur, nums[i])
+		backtrace(nums, i+1, num, cur)
+		cur = cur[:len(cur)-1]
+	}
+}

leetcode/0078.subsets/subsets_test.go

@@ -0,0 +1,20 @@
+package leetcode
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSubsets(t *testing.T) {
+	assert.ElementsMatch(t, [][]int{
+		{3},
+		{1},
+		{2},
+		{1, 2, 3},
+		{1, 3},
+		{2, 3},
+		{1, 2},
+		{},
+	}, subsets([]int{1, 2, 3}))
+}