From 28058028159bc15a70d77fd3b60a3c92d23108cd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=83=91=E6=B1=89=E5=8D=BF?= <15176331678@163.com>
Date: Mon, 10 Jun 2019 17:59:07 +0800
Subject: [PATCH 1/5] =?UTF-8?q?new=20dir=20=E5=AE=B6?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 "Recursion/\345\256\266/.keep" | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 "Recursion/\345\256\266/.keep"

diff --git "a/Recursion/\345\256\266/.keep" "b/Recursion/\345\256\266/.keep"
new file mode 100644
index 0000000..e69de29
-- 
Gitee


From 374df7db407bd1a80e15ec92a8188eb7bc0507c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=83=91=E6=B1=89=E5=8D=BF?= <15176331678@163.com>
Date: Mon, 10 Jun 2019 18:06:59 +0800
Subject: [PATCH 2/5] 1112231

---
 "Recursion/\345\256\266/\345\256\266_46" | 32 ++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 "Recursion/\345\256\266/\345\256\266_46"

diff --git "a/Recursion/\345\256\266/\345\256\266_46" "b/Recursion/\345\256\266/\345\256\266_46"
new file mode 100644
index 0000000..a5a25d7
--- /dev/null
+++ "b/Recursion/\345\256\266/\345\256\266_46"
@@ -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
-- 
Gitee


From 8442f57b37105525aceacdd44f1ca60e7e75fb56 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=83=91=E6=B1=89=E5=8D=BF?= <15176331678@163.com>
Date: Mon, 10 Jun 2019 18:12:18 +0800
Subject: [PATCH 3/5] 12312312313

---
 "Recursion/\345\256\266/\345\256\266_77.md" | 23 +++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 "Recursion/\345\256\266/\345\256\266_77.md"

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 0000000..e2ba412
--- /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
-- 
Gitee


From 30eeb7793a2115999a89a93580406ad6bc2b7d29 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=83=91=E6=B1=89=E5=8D=BF?= <15176331678@163.com>
Date: Mon, 10 Jun 2019 18:12:43 +0800
Subject: [PATCH 4/5] =?UTF-8?q?=E9=87=8D=E5=91=BD=E5=90=8D=E6=96=87?=
 =?UTF-8?q?=E4=BB=B6Recursion/=E5=AE=B6/=E5=AE=B6=5F46=E4=B8=BARecursion/?=
 =?UTF-8?q?=E5=AE=B6/=E5=AE=B6=5F46.md?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../\345\256\266/\345\256\266_46.md"                              | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename "Recursion/\345\256\266/\345\256\266_46" => "Recursion/\345\256\266/\345\256\266_46.md" (100%)

diff --git "a/Recursion/\345\256\266/\345\256\266_46" "b/Recursion/\345\256\266/\345\256\266_46.md"
similarity index 100%
rename from "Recursion/\345\256\266/\345\256\266_46"
rename to "Recursion/\345\256\266/\345\256\266_46.md"
-- 
Gitee


From 9cdd1ed840a72417b811439ddd69951092ee3148 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=83=91=E6=B1=89=E5=8D=BF?= <15176331678@163.com>
Date: Mon, 10 Jun 2019 18:15:46 +0800
Subject: [PATCH 5/5] 123412341234

---
 "Recursion/\345\256\266/\345\256\266_69.md" | 23 +++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 "Recursion/\345\256\266/\345\256\266_69.md"

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 0000000..f7cdc01
--- /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
-- 
Gitee