From 413ec11ba241e89c3128e1f51b40e95527fe8ccc Mon Sep 17 00:00:00 2001
From: BGMer7 <caijinyang98@gmail.com>
Date: Sat, 30 Apr 2022 14:39:20 +0800
Subject: [PATCH 1/3] =?UTF-8?q?908.=20=E6=9C=80=E5=B0=8F=E5=B7=AE=E5=80=BC?=
 =?UTF-8?q?I?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/com/gatsby/_908SmallestRangeI.java | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 src/com/gatsby/_908SmallestRangeI.java

diff --git a/src/com/gatsby/_908SmallestRangeI.java b/src/com/gatsby/_908SmallestRangeI.java
new file mode 100644
index 0000000..2d098c2
--- /dev/null
+++ b/src/com/gatsby/_908SmallestRangeI.java
@@ -0,0 +1,20 @@
+package com.gatsby;
+
+/**
+ * @author -- gatsby
+ * @date -- 2022/4/30
+ * @description -- leetcode 908 最小差值
+ */
+
+
+public class _908SmallestRangeI {
+    public int smallestRangeI(int[] nums, int k) {
+        int max = Integer.MIN_VALUE;
+        int min = Integer.MAX_VALUE;
+        for (int num : nums) {
+            if (num > max) max = num;
+            if (num < min) min = num;
+        }
+        return max - min > 2 * k ? max - min - 2 * k : 0;
+    }
+}
\ No newline at end of file

From a6c7c4458c80554834117039e6eb3479938d6490 Mon Sep 17 00:00:00 2001
From: BGMer7 <caijinyang98@gmail.com>
Date: Tue, 12 Jul 2022 17:14:00 +0800
Subject: [PATCH 2/3] 208. Implement Trie (Prefix Tree)

---
 src/com/gatsby/_208ImplementTrie.java | 55 +++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 src/com/gatsby/_208ImplementTrie.java

diff --git a/src/com/gatsby/_208ImplementTrie.java b/src/com/gatsby/_208ImplementTrie.java
new file mode 100644
index 0000000..1f021a8
--- /dev/null
+++ b/src/com/gatsby/_208ImplementTrie.java
@@ -0,0 +1,55 @@
+package com.gatsby;
+
+/**
+ * @author -- gatsby
+ * @date -- 2022/7/12
+ * @description --
+ */
+
+
+public class _208ImplementTrie {
+    class TrieNode {
+        boolean isEnd = false;
+        // 直接创建一个26字母的数组，这样已经可以考虑到所有的下一位字母的情况
+        TrieNode[] children = new TrieNode[26];
+    }
+
+    private TrieNode root;
+
+    public _208ImplementTrie() {
+        root = new TrieNode();
+    }
+
+    public void insert(String word) {
+        TrieNode p = root;
+        for (int i = 0; i < word.length(); ++i) {
+            int letter = word.charAt(i) - 'a';
+            if (p.children[letter] == null) {
+                p.children[letter] = new TrieNode();
+            }
+            p = p.children[letter];
+        }
+        // 此时在最后一个字母，将isEnd置为true
+        p.isEnd = true;
+    }
+
+    public boolean search(String word) {
+        TrieNode p = root;
+        for (int i = 0; i < word.length(); ++i) {
+            int letter = word.charAt(i) - 'a';
+            if (p.children[letter] == null) return false;
+            else p = p.children[letter];
+        }
+        return p.isEnd;
+    }
+
+    public boolean startsWith(String prefix) {
+        TrieNode p = root;
+        for (int i = 0; i < prefix.length(); ++i) {
+            int letter = prefix.charAt(i) - 'a';
+            if (p.children[letter] == null) return false;
+            else p = p.children[letter];
+        }
+        return true;
+    }
+}
\ No newline at end of file

From edbbbbb8d5ca1d1247ee1708cc79061196054ba1 Mon Sep 17 00:00:00 2001
From: BGMer7 <caijinyang98@gmail.com>
Date: Wed, 13 Jul 2022 15:29:40 +0800
Subject: [PATCH 3/3] =?UTF-8?q?=E5=89=91=E6=8C=87OfferII=20004.=20?=
 =?UTF-8?q?=E5=8F=AA=E5=87=BA=E7=8E=B0=E4=B8=80=E6=AC=A1=E7=9A=84=E6=95=B0?=
 =?UTF-8?q?=E5=AD=97?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/com/gatsby/offerII/_4OnlyOnce.java | 40 ++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 src/com/gatsby/offerII/_4OnlyOnce.java

diff --git a/src/com/gatsby/offerII/_4OnlyOnce.java b/src/com/gatsby/offerII/_4OnlyOnce.java
new file mode 100644
index 0000000..8697a72
--- /dev/null
+++ b/src/com/gatsby/offerII/_4OnlyOnce.java
@@ -0,0 +1,40 @@
+package com.gatsby.offerII;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * @author -- gatsby
+ * @date -- 2022/7/13
+ * @description -- 剑指 Offer II 004. 只出现一次的数字
+ */
+
+
+public class _4OnlyOnce {
+    public int singleNumber(int[] nums) {
+        Map<Integer, Integer> count = new HashMap<>();
+        for (int num : nums) {
+            count.put(num, count.getOrDefault(num, 0) + 1);
+        }
+
+        for (int num : count.keySet()) {
+            if (count.get(num) == 1) return num;
+        }
+
+        return -1;
+    }
+
+    public int single(int start, int[] nums) {
+        return nums[start] ^ nums[start + 1] ^ nums[start + 2];
+    }
+
+    public int singleNumberSort(int[] nums) {
+        Arrays.sort(nums);
+
+        for (int i = 0; i + 3 < nums.length; i += 3) {
+            if (nums[i] != nums[i+2]) return single(i, nums);
+        }
+        return -1;
+    }
+}
\ No newline at end of file