add new solutions

solutions/0/q46/solution.go

@@ -0,0 +1,34 @@
+package q46
+
+func recurse(nums []int, offset int, buf []int, seen []bool, ret [][]int) [][]int {
+	if offset == len(nums) {
+		a := make([]int, len(buf))
+		copy(a, buf)
+		return append(ret, a)
+	}
+
+	for i := range nums {
+		if seen[i] {
+			continue
+		}
+		seen[i] = true
+		buf[offset] = nums[i]
+		ret = recurse(nums, offset+1, buf, seen, ret)
+		seen[i] = false
+	}
+	return ret
+}
+
+func permute(nums []int) [][]int {
+	totalLen := 1
+	for i := range len(nums) {
+		totalLen *= i + 1
+	}
+	ret := make([][]int, 0, totalLen)
+	buf := make([]int, len(nums))
+	seen := make([]bool, len(nums))
+
+	return recurse(nums, 0, buf, seen, ret)
+}
+
+var _ = permute