From ff5fda441c7bce8e1cae631670b7f3e06ff8177c Mon Sep 17 00:00:00 2001
From: xsplus <960346496@qq.com>
Date: Sun, 14 Jul 2019 15:37:34 +0800
Subject: [PATCH 1/2] =?UTF-8?q?Week=5F04=E4=BD=9C=E4=B8=9A?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .idea/algorithm.iml            |   8 --
 .idea/misc.xml                 |   6 -
 .idea/modules.xml              |   8 --
 .idea/vcs.xml                  |   6 -
 .idea/workspace.xml            | 227 ---------------------------------
 Week_04/id_6/LeetCode_053_6.go |  33 +++++
 Week_04/id_6/LeetCode_169_6.go |  80 ++++++++++++
 Week_04/id_6/LeetCode_208_6.go |  65 ++++++++++
 Week_04/id_6/LeetCode_211_6.go |  57 +++++++++
 Week_04/id_6/LeetCode_240_6.go |  69 ++++++++++
 Week_04/id_6/LeetCode_455_6.go |  25 ++++
 Week_04/id_6/LeetCode_714_6.go |  29 +++++
 Week_04/id_6/LeetCode_720_6.go |  40 ++++++
 13 files changed, 398 insertions(+), 255 deletions(-)
 delete mode 100644 .idea/algorithm.iml
 delete mode 100644 .idea/misc.xml
 delete mode 100644 .idea/modules.xml
 delete mode 100644 .idea/vcs.xml
 delete mode 100644 .idea/workspace.xml
 create mode 100644 Week_04/id_6/LeetCode_053_6.go
 create mode 100644 Week_04/id_6/LeetCode_169_6.go
 create mode 100644 Week_04/id_6/LeetCode_208_6.go
 create mode 100644 Week_04/id_6/LeetCode_211_6.go
 create mode 100644 Week_04/id_6/LeetCode_240_6.go
 create mode 100644 Week_04/id_6/LeetCode_455_6.go
 create mode 100644 Week_04/id_6/LeetCode_714_6.go
 create mode 100644 Week_04/id_6/LeetCode_720_6.go

diff --git a/.idea/algorithm.iml b/.idea/algorithm.iml
deleted file mode 100644
index c956989b..00000000
--- a/.idea/algorithm.iml
+++ /dev/null
@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="WEB_MODULE" version="4">
-  <component name="NewModuleRootManager">
-    <content url="file://$MODULE_DIR$" />
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-  </component>
-</module>
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
deleted file mode 100644
index 28a804d8..00000000
--- a/.idea/misc.xml
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="JavaScriptSettings">
-    <option name="languageLevel" value="ES6" />
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/modules.xml b/.idea/modules.xml
deleted file mode 100644
index 2ba6d76a..00000000
--- a/.idea/modules.xml
+++ /dev/null
@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ProjectModuleManager">
-    <modules>
-      <module fileurl="file://$PROJECT_DIR$/.idea/algorithm.iml" filepath="$PROJECT_DIR$/.idea/algorithm.iml" />
-    </modules>
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/vcs.xml b/.idea/vcs.xml
deleted file mode 100644
index 94a25f7f..00000000
--- a/.idea/vcs.xml
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="VcsDirectoryMappings">
-    <mapping directory="$PROJECT_DIR$" vcs="Git" />
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
deleted file mode 100644
index e637ba49..00000000
--- a/.idea/workspace.xml
+++ /dev/null
@@ -1,227 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ChangeListManager">
-    <list default="true" id="ba273464-1eeb-4636-91f5-cacf4e988720" name="Default Changelist" comment="" />
-    <option name="EXCLUDED_CONVERTED_TO_IGNORED" value="true" />
-    <option name="SHOW_DIALOG" value="false" />
-    <option name="HIGHLIGHT_CONFLICTS" value="true" />
-    <option name="HIGHLIGHT_NON_ACTIVE_CHANGELIST" value="false" />
-    <option name="LAST_RESOLUTION" value="IGNORE" />
-  </component>
-  <component name="FileEditorManager">
-    <leaf>
-      <file pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_102_6.go">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="747">
-              <caret line="69" column="1" selection-start-line="69" selection-start-column="1" selection-end-line="69" selection-end-column="1" />
-            </state>
-          </provider>
-        </entry>
-      </file>
-      <file pinned="false" current-in-tab="true">
-        <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_104_6.go">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="72">
-              <caret line="4" column="1" lean-forward="true" selection-start-line="4" selection-start-column="1" selection-end-line="4" selection-end-column="1" />
-              <folding>
-                <element signature="e#14#31#0" expanded="true" />
-              </folding>
-            </state>
-          </provider>
-        </entry>
-      </file>
-      <file pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_111_6.go">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="747">
-              <caret line="68" column="1" selection-start-line="68" selection-start-column="1" selection-end-line="68" selection-end-column="1" />
-            </state>
-          </provider>
-        </entry>
-      </file>
-      <file pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_200_6.go">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="1566">
-              <caret line="87" column="1" selection-start-line="87" selection-start-column="1" selection-end-line="87" selection-end-column="1" />
-            </state>
-          </provider>
-        </entry>
-      </file>
-      <file pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_210_6.go">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="144">
-              <caret line="8" lean-forward="true" selection-start-line="8" selection-end-line="8" />
-            </state>
-          </provider>
-        </entry>
-      </file>
-    </leaf>
-  </component>
-  <component name="FileTemplateManagerImpl">
-    <option name="RECENT_TEMPLATES">
-      <list>
-        <option value="Go File" />
-      </list>
-    </option>
-  </component>
-  <component name="GOROOT" path="/usr/local/Cellar/go/1.12.6/libexec" />
-  <component name="Git.Settings">
-    <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$" />
-  </component>
-  <component name="IdeDocumentHistory">
-    <option name="CHANGED_PATHS">
-      <list>
-        <option value="$PROJECT_DIR$/Week_03/id_6/0200.go" />
-        <option value="$PROJECT_DIR$/Week_03/id_6/LeetCode_210_6.go" />
-        <option value="$PROJECT_DIR$/Week_03/id_6/LeetCode_200_6.go" />
-        <option value="$PROJECT_DIR$/Week_03/id_6/LeetCode_111_6.go" />
-        <option value="$PROJECT_DIR$/Week_03/id_6/LeetCode_102_6.go" />
-        <option value="$PROJECT_DIR$/Week_03/id_6/LeetCode_104_6.go" />
-      </list>
-    </option>
-  </component>
-  <component name="ProjectFrameBounds" fullScreen="true">
-    <option name="width" value="1440" />
-    <option name="height" value="900" />
-  </component>
-  <component name="ProjectView">
-    <navigator proportions="" version="1">
-      <foldersAlwaysOnTop value="true" />
-    </navigator>
-    <panes>
-      <pane id="ProjectPane">
-        <subPane>
-          <expand>
-            <path>
-              <item name="algorithm" type="b2602c69:ProjectViewProjectNode" />
-              <item name="algorithm" type="462c0819:PsiDirectoryNode" />
-            </path>
-            <path>
-              <item name="algorithm" type="b2602c69:ProjectViewProjectNode" />
-              <item name="algorithm" type="462c0819:PsiDirectoryNode" />
-              <item name="Week_02" type="462c0819:PsiDirectoryNode" />
-            </path>
-            <path>
-              <item name="algorithm" type="b2602c69:ProjectViewProjectNode" />
-              <item name="algorithm" type="462c0819:PsiDirectoryNode" />
-              <item name="Week_02" type="462c0819:PsiDirectoryNode" />
-              <item name="id_6" type="462c0819:PsiDirectoryNode" />
-            </path>
-            <path>
-              <item name="algorithm" type="b2602c69:ProjectViewProjectNode" />
-              <item name="algorithm" type="462c0819:PsiDirectoryNode" />
-              <item name="Week_03" type="462c0819:PsiDirectoryNode" />
-            </path>
-            <path>
-              <item name="algorithm" type="b2602c69:ProjectViewProjectNode" />
-              <item name="algorithm" type="462c0819:PsiDirectoryNode" />
-              <item name="Week_03" type="462c0819:PsiDirectoryNode" />
-              <item name="id_6" type="462c0819:PsiDirectoryNode" />
-            </path>
-          </expand>
-          <select />
-        </subPane>
-      </pane>
-      <pane id="Scope" />
-    </panes>
-  </component>
-  <component name="PropertiesComponent">
-    <property name="DefaultGoTemplateProperty" value="Go File" />
-    <property name="WebServerToolWindowFactoryState" value="false" />
-    <property name="go.gopath.indexing.explicitly.defined" value="true" />
-    <property name="go.import.settings.migrated" value="true" />
-    <property name="go.sdk.automatically.set" value="true" />
-    <property name="last_opened_file_path" value="$USER_HOME$" />
-    <property name="nodejs_interpreter_path.stuck_in_default_project" value="undefined stuck path" />
-    <property name="nodejs_npm_path_reset_for_default_project" value="true" />
-  </component>
-  <component name="RunDashboard">
-    <option name="ruleStates">
-      <list>
-        <RuleState>
-          <option name="name" value="ConfigurationTypeDashboardGroupingRule" />
-        </RuleState>
-        <RuleState>
-          <option name="name" value="StatusDashboardGroupingRule" />
-        </RuleState>
-      </list>
-    </option>
-  </component>
-  <component name="ToolWindowManager">
-    <frame x="0" y="0" width="1440" height="900" extended-state="0" />
-    <editor active="true" />
-    <layout>
-      <window_info active="true" content_ui="combo" id="Project" order="0" visible="true" weight="0.2532189" />
-      <window_info id="Structure" order="1" side_tool="true" weight="0.25" />
-      <window_info id="Favorites" order="2" side_tool="true" />
-      <window_info anchor="bottom" id="Message" order="0" />
-      <window_info anchor="bottom" id="Find" order="1" />
-      <window_info anchor="bottom" id="Run" order="2" />
-      <window_info anchor="bottom" id="Debug" order="3" weight="0.4" />
-      <window_info anchor="bottom" id="Cvs" order="4" weight="0.25" />
-      <window_info anchor="bottom" id="Inspection" order="5" weight="0.4" />
-      <window_info anchor="bottom" id="TODO" order="6" />
-      <window_info anchor="bottom" id="Docker" order="7" show_stripe_button="false" />
-      <window_info anchor="bottom" id="Database Changes" order="8" />
-      <window_info anchor="bottom" id="Version Control" order="9" />
-      <window_info anchor="bottom" id="Terminal" order="10" />
-      <window_info anchor="bottom" id="Event Log" order="11" side_tool="true" />
-      <window_info anchor="right" id="Commander" internal_type="SLIDING" order="0" type="SLIDING" weight="0.4" />
-      <window_info anchor="right" id="Ant Build" order="1" weight="0.25" />
-      <window_info anchor="right" content_ui="combo" id="Hierarchy" order="2" weight="0.25" />
-      <window_info anchor="right" id="leetcode" order="3" side_tool="true" />
-      <window_info anchor="right" id="Database" order="4" />
-    </layout>
-  </component>
-  <component name="TypeScriptGeneratedFilesManager">
-    <option name="version" value="1" />
-  </component>
-  <component name="editorHistoryManager">
-    <entry file="file://$PROJECT_DIR$/Week_02/id_6/LeetCode_1_6.go">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="-135" />
-      </provider>
-    </entry>
-    <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_210_6.go">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="144">
-          <caret line="8" lean-forward="true" selection-start-line="8" selection-end-line="8" />
-        </state>
-      </provider>
-    </entry>
-    <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_200_6.go">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="1566">
-          <caret line="87" column="1" selection-start-line="87" selection-start-column="1" selection-end-line="87" selection-end-column="1" />
-        </state>
-      </provider>
-    </entry>
-    <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_111_6.go">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="747">
-          <caret line="68" column="1" selection-start-line="68" selection-start-column="1" selection-end-line="68" selection-end-column="1" />
-        </state>
-      </provider>
-    </entry>
-    <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_102_6.go">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="747">
-          <caret line="69" column="1" selection-start-line="69" selection-start-column="1" selection-end-line="69" selection-end-column="1" />
-        </state>
-      </provider>
-    </entry>
-    <entry file="file://$PROJECT_DIR$/Week_03/id_6/LeetCode_104_6.go">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="72">
-          <caret line="4" column="1" lean-forward="true" selection-start-line="4" selection-start-column="1" selection-end-line="4" selection-end-column="1" />
-          <folding>
-            <element signature="e#14#31#0" expanded="true" />
-          </folding>
-        </state>
-      </provider>
-    </entry>
-  </component>
-</project>
\ No newline at end of file
diff --git a/Week_04/id_6/LeetCode_053_6.go b/Week_04/id_6/LeetCode_053_6.go
new file mode 100644
index 00000000..962b0a71
--- /dev/null
+++ b/Week_04/id_6/LeetCode_053_6.go
@@ -0,0 +1,33 @@
+package main
+
+import "fmt"
+
+/**
+时间复杂度：O(n)
+空间复杂度：O(1)
+ */
+func maxSubArray(nums []int) int {
+	answer := nums[0]
+	sum := 0
+	for _, v := range nums{
+		if sum > 0 {
+			sum += v
+		}else {
+			// 如果 sum 小于 0 那还不如从当前位置开始计算
+			sum = v
+		}
+		answer = maxInt(sum, answer)
+	}
+	return answer
+}
+
+func maxInt(a int, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func main()  {
+	fmt.Println("结果是：", maxSubArray([]int{-2,1,-3,4,-1,2,1,-5,4}))
+}
\ No newline at end of file
diff --git a/Week_04/id_6/LeetCode_169_6.go b/Week_04/id_6/LeetCode_169_6.go
new file mode 100644
index 00000000..2ac323cc
--- /dev/null
+++ b/Week_04/id_6/LeetCode_169_6.go
@@ -0,0 +1,80 @@
+package main
+
+import "fmt"
+
+/**
+暴力法
+时间复杂度：O(n^2)
+空间复杂度：O(1)
+ */
+func majorityElement(nums []int) int {
+	majorityCount := len(nums)/2
+	for _, v := range nums {
+		count := 0
+		for _, num := range nums {
+			if v == num {
+				count++
+			}
+		}
+		if count > majorityCount {
+			return v
+		}
+	}
+	return -1
+}
+
+/**
+哈希表
+时间复杂度：O(n)
+空间复杂度：O(n)
+ */
+func majorityElement1(nums []int) int {
+	majorityCount := len(nums)/2
+	m := make(map[int]int, len(nums))
+	for _, num := range nums {
+		if _, ok := m[num]; ok {
+			m[num]++
+		}else {
+			m[num] = 1
+		}
+	}
+	for k := range m {
+		if m[k] > majorityCount {
+			return k
+		}
+	}
+	return -1
+}
+
+/**
+Boyer-Moore 投票算法 (当不存在众数的时候此方法不适合)
+时间复杂度：O(n)
+空间复杂度：O(1)
+*/
+func majorityElement2(nums []int) int {
+	count := 0
+	var candidate int
+
+	for _, num := range nums {
+		if count == 0 {
+			candidate = num
+		}
+		if num == candidate {
+			count += 1
+		}else {
+			count -= 1
+		}
+	}
+	return candidate
+}
+
+func main()  {
+	nums := []int{3,2,3}
+	fmt.Println("结果是：", majorityElement(nums))
+
+	nums1 := []int{3,2,3}
+	fmt.Println("结果是：", majorityElement1(nums1))
+
+	nums2 := []int{3,2,3}
+	fmt.Println("结果是：", majorityElement2(nums2))
+}
\ No newline at end of file
diff --git a/Week_04/id_6/LeetCode_208_6.go b/Week_04/id_6/LeetCode_208_6.go
new file mode 100644
index 00000000..822f7d0d
--- /dev/null
+++ b/Week_04/id_6/LeetCode_208_6.go
@@ -0,0 +1,65 @@
+package main
+
+type Trie struct {
+	val byte
+	sons [26]*Trie
+	end int
+}
+
+func Constructor() Trie {
+	return Trie{}
+}
+
+/**
+时间复杂度：O(m)   m 为 字符串长度
+空间复杂度：O(m)
+ */
+func (this *Trie) Insert(word string)  {
+	node := this
+	size := len(word)
+	for i := 0; i < size; i++ {
+		idx := word[i] - 'a'
+		if node.sons[idx] == nil {
+			node.sons[idx] = &Trie{val:word[i]}
+		}
+		node = node.sons[idx]
+	}
+	node.end++
+}
+
+/**
+时间复杂度：O(m)
+空间复杂度：O(1)
+ */
+func (this *Trie) Search(word string) bool {
+	node := this
+	size := len(word)
+	for i := 0; i < size; i++  {
+		idx := word[i] - 'a'
+		if node.sons[idx] == nil {
+			return false
+		}
+		node = node.sons[idx]
+	}
+	if node.end > 0 {
+		return true
+	}
+	return false
+}
+
+/**
+时间复杂度：O(m)
+空间复杂度：O(1)
+*/
+func (this *Trie) StartsWith(prefix string) bool {
+	node := this
+	size := len(prefix)
+	for i := 0; i < size; i++  {
+		idx := prefix[i] - 'a'
+		if node.sons[idx] == nil {
+			return false
+		}
+		node = node.sons[idx]
+	}
+	return true
+}
\ No newline at end of file
diff --git a/Week_04/id_6/LeetCode_211_6.go b/Week_04/id_6/LeetCode_211_6.go
new file mode 100644
index 00000000..760b7d2d
--- /dev/null
+++ b/Week_04/id_6/LeetCode_211_6.go
@@ -0,0 +1,57 @@
+package main
+
+type WordDictionary struct {
+	sons [26]*WordDictionary
+	end int
+}
+
+
+func Constructor() WordDictionary {
+	return WordDictionary{}
+}
+
+func (this *WordDictionary) AddWord(word string)  {
+	for _, c := range word {
+		idx := c - 'a'
+		if this.sons[idx] == nil {
+			this.sons[idx] = &WordDictionary{}
+		}
+		this = this.sons[idx]
+	}
+	this.end++
+}
+
+
+func (this *WordDictionary) Search(word string) bool {
+	for i, c := range word {
+		if c != '.' {
+			idx := c - 'a'
+			if this.sons[idx] == nil {
+				return false
+			}
+			this = this.sons[idx]
+		}else {
+			for _, son := range this.sons {
+				if son == nil {
+					continue
+				}
+				this = son
+				if i == len(word) - 1 {
+					if this.end > 0 {
+						return true
+					}
+					continue
+				}
+				if this.Search(word[(i+1):]) {
+					return true
+				}
+			}
+			return false
+		}
+	}
+
+	if this.end > 0 {
+		return true
+	}
+	return false
+}
\ No newline at end of file
diff --git a/Week_04/id_6/LeetCode_240_6.go b/Week_04/id_6/LeetCode_240_6.go
new file mode 100644
index 00000000..40a7cc4a
--- /dev/null
+++ b/Week_04/id_6/LeetCode_240_6.go
@@ -0,0 +1,69 @@
+package main
+
+import "fmt"
+
+/**
+暴力法
+时间复杂度：O(m*n)
+空间复杂度：O(1)
+ */
+func searchMatrix(matrix [][]int, target int) bool {
+	for _, v := range matrix {
+		for _, vv := range v {
+			if vv == target {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+
+/**
+暴力法 优化版 （利用矩阵  左到右升序  上到下 升序 的特性）
+空间复杂度：O(1)
+*/
+func searchMatrix1(matrix [][]int, target int) bool {
+	m := len(matrix)
+	if m == 0 {
+		return false
+	}
+	n := len(matrix[0])
+	if n == 0 {
+		return false
+	}
+
+	i, j := m-1, 0
+	for i >= 0 && j < n  {
+		if matrix[i][j] == target {
+			return true
+		}
+		if matrix[i][j] > target {
+			// 排除 右侧元素，往上找
+			i--
+		}else {
+			// 继续往右找
+			j++
+		}
+	}
+
+	return false
+}
+
+
+func main()  {
+	//matrix := [][]int{
+	//	{1,   4,  7, 11, 15},
+	//	{2,   5,  8, 12, 19},
+	//	{3,   6,  9, 16, 22},
+	//	{10, 13, 14, 17, 24},
+	//	{18, 21, 23, 26, 30},
+	//}
+
+	matrix := [][]int{
+		{5},
+		{6},
+	}
+	fmt.Println("结果是：", searchMatrix(matrix, 5))
+	fmt.Println("结果是：", searchMatrix1(matrix, 5))
+}
\ No newline at end of file
diff --git a/Week_04/id_6/LeetCode_455_6.go b/Week_04/id_6/LeetCode_455_6.go
new file mode 100644
index 00000000..e5517556
--- /dev/null
+++ b/Week_04/id_6/LeetCode_455_6.go
@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+	"sort"
+)
+
+func findContentChildren(g []int, s []int) int {
+	sort.Ints(g)
+	sort.Ints(s)
+
+	var i, j, res int
+	for i < len(g) && j < len(s)  {
+		if s[j] >= g[i] {
+			i++
+			res++
+		}
+		j++
+	}
+	return res
+}
+
+func main()  {
+	fmt.Println("结果是：", findContentChildren([]int{1,2,3}, []int{1,1}))
+}
\ No newline at end of file
diff --git a/Week_04/id_6/LeetCode_714_6.go b/Week_04/id_6/LeetCode_714_6.go
new file mode 100644
index 00000000..c4cd6c2f
--- /dev/null
+++ b/Week_04/id_6/LeetCode_714_6.go
@@ -0,0 +1,29 @@
+package main
+
+import "fmt"
+
+/**
+时间复杂度：O(n)
+空间复杂度：O(1)
+ */
+func maxProfit(prices []int, fee int) int {
+	empty := 0 // 不持有股票时最大利润
+	hold := -prices[0] // 持有股票最大利润
+
+	for i := 1; i < len(prices); i++ {
+		empty = max(empty, hold + prices[i] - fee)
+		hold = max(hold, empty - prices[i])
+	}
+	return empty
+}
+
+func max(a int, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func main()  {
+	fmt.Println("结果是：", maxProfit([]int{1, 3, 2, 8, 4, 9}, 2))
+}
\ No newline at end of file
diff --git a/Week_04/id_6/LeetCode_720_6.go b/Week_04/id_6/LeetCode_720_6.go
new file mode 100644
index 00000000..2cabe6db
--- /dev/null
+++ b/Week_04/id_6/LeetCode_720_6.go
@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+	"sort"
+)
+
+/**
+时间复杂度：O(n)
+空间复杂度：O(n)
+ */
+func longestWord(words []string) string {
+	if len(words) == 0 {
+		return ""
+	}
+
+	sort.Strings(words)
+	// 初始化 m 存放"合格"的单词
+	m := make(map[string]bool, len(words))
+
+	res := words[0]
+
+	for _, w := range words {
+		n := len(w)
+		if n == 1 {
+			m[w] = true
+		}else if m[w[:(n-1)]] {
+			m[w] = true
+			if n > len(res) {
+				res = w
+			}
+		}
+	}
+	return res
+}
+
+func main()  {
+	words := []string{"a", "banana", "app", "appl", "ap", "apply", "apple"}
+	fmt.Println("结果是：", longestWord(words))
+}

From 6288c2f0dedb50bf77828f119eb12d17d6f16d49 Mon Sep 17 00:00:00 2001
From: xsplus <960346496@qq.com>
Date: Sun, 14 Jul 2019 15:40:38 +0800
Subject: [PATCH 2/2] =?UTF-8?q?=E4=BF=AE=E6=94=B9gitignore?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .gitignore | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.gitignore b/.gitignore
index e43b0f98..4befed30 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 .DS_Store
+.idea