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top-100-liked/55/leetcode_test.go

@@ -0,0 +1,41 @@
+package top100liked
+
+import (
+	"fmt"
+	"testing"
+)
+
+// https://leetcode.cn/problems/permutations?envType=study-plan-v2&envId=top-100-liked
+
+func permute(nums []int) [][]int {
+	l := len(nums)
+	fact := 1
+	for i := 2; i <= l; i++ {
+		fact *= i
+	}
+	res := make([][]int, 0, fact)
+	var helper func(nums []int, used []bool, r []int)
+	helper = func(nums []int, used []bool, r []int) {
+		for i, v := range used {
+			if !v {
+				used[i] = true
+				r = append(r, nums[i])
+				if len(r) == l {
+					cp := make([]int, l)
+					copy(cp, r)
+					res = append(res, cp)
+				} else {
+					helper(nums, used, r)
+				}
+				r = r[:len(r)-1]
+				used[i] = false
+			}
+		}
+	}
+	helper(nums, make([]bool, l), make([]int, 0))
+	return res
+}
+
+func Test(t *testing.T) {
+	fmt.Printf("%+v", permute([]int{5, 4, 6, 2}))
+}