diff --git "a/Recursion/\345\256\266/.keep" "b/Recursion/\345\256\266/.keep"
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git "a/Recursion/\345\256\266/\345\256\266_46.md" "b/Recursion/\345\256\266/\345\256\266_46.md"
new file mode 100644
index 0000000000000000000000000000000000000000..a5a25d7b1cc06e9289181e26d70ff3f2c47b666c
--- /dev/null
+++ "b/Recursion/\345\256\266/\345\256\266_46.md"
@@ -0,0 +1,32 @@
+```
+/**
+ * 作者：家
+ * 思路：回溯，循环+递归，用一个Map记录访问过的元素即可
+ * 时间复杂度：O(n^2)?不是很确定，用了Map可以保证获取重复元素时为O(1)
+ * 空间复杂度：O(n),递归最多到n层，加上n长度的Map
+ */
+ func permute(nums []int) [][]int {
+    l := len(nums)
+    if l == 0 {
+        return [][]int{}
+    }
+    var dfs func([]int)
+    have := map[int]bool{}
+    re := [][]int{}
+    dfs = func(r []int) {
+        if len(r) == l {
+            re = append(re,append([]int{},r...))
+            return
+        }
+        for i:=0;i<l;i++ {
+            if !have[i]{
+                have[i] = true
+                dfs(append(r,nums[i]))
+                have[i] = false
+            }
+        }
+    }
+    dfs([]int{})
+    return re
+}
+```
\ No newline at end of file
diff --git "a/Recursion/\345\256\266/\345\256\266_69.md" "b/Recursion/\345\256\266/\345\256\266_69.md"
new file mode 100644
index 0000000000000000000000000000000000000000..f7cdc01d3335fa24ff14f5ebcdbaa0355f589142
--- /dev/null
+++ "b/Recursion/\345\256\266/\345\256\266_69.md"
@@ -0,0 +1,23 @@
+```
+/**
+ * 作者：家
+ * 思路：二分法即可，思路比较简单，可以通过牛顿法优化
+ * 时间复杂度：O(logN)
+ * 空间复杂度：O(logN)?不是很确定，貌似最多递归logN层
+ */
+func mySqrt(x int) int {
+    return rec(x,0,x)
+}
+func rec(x int, l int, r int) int{
+    mid := l+(r-l)/2
+    now := mid*mid
+    if now == x || now < x && (mid+1)*(mid+1) > x{
+        return mid
+    }else if now > x {
+        return rec(x,l,mid-1)
+    }
+    return rec(x,mid+1,r)
+}
+
+
+```
\ No newline at end of file
diff --git "a/Recursion/\345\256\266/\345\256\266_77.md" "b/Recursion/\345\256\266/\345\256\266_77.md"
new file mode 100644
index 0000000000000000000000000000000000000000..e2ba412a6c1a42295bd393e221a55fbe3f70df3d
--- /dev/null
+++ "b/Recursion/\345\256\266/\345\256\266_77.md"
@@ -0,0 +1,23 @@
+```
+/**
+ * 作者：家
+ * 思路：回溯，循环+递归标配
+ * 时间复杂度：O(n*k)?不是很确定，循环n次(递减的等差数列)*递归k次
+ * 空间复杂度：O(k),递归最多到k层
+ */
+func combine(n int, k int) [][]int {
+    re := [][]int{}
+    var dfs func(int,[]int)
+    dfs = func(index int,r []int) {
+        if len(r) == k {
+            re = append(re,append([]int{},r...))
+            return
+        }
+        for i:=index;i<=n;i++ {
+            dfs(i+1,append(r,i))
+        }
+    }
+    dfs(1,[]int{})
+    return re
+}
+```
\ No newline at end of file