From 59f245dda7cd33d0f00f8073e84659c07e257836 Mon Sep 17 00:00:00 2001
From: wu xiangkai <wuxiangkai@yonyou.com>
Date: Thu, 23 Oct 2025 10:33:53 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20=E5=8F=8C=E6=8C=87=E9=92=88?=
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---
 26.remove-duplicates-from-sorted-array.java   | 24 +++++++++++++++++
 27.remove-element.java                        | 21 +++++++++++++++
 ...x-of-the-first-occurrence-in-a-string.java | 24 +++++++++++++++++
 ...emove-duplicates-from-sorted-array-ii.java | 26 +++++++++++++++++++
 4 files changed, 95 insertions(+)
 create mode 100644 26.remove-duplicates-from-sorted-array.java
 create mode 100644 27.remove-element.java
 create mode 100644 28.find-the-index-of-the-first-occurrence-in-a-string.java
 create mode 100644 80.remove-duplicates-from-sorted-array-ii.java

diff --git a/26.remove-duplicates-from-sorted-array.java b/26.remove-duplicates-from-sorted-array.java
new file mode 100644
index 0000000..39c8a7d
--- /dev/null
+++ b/26.remove-duplicates-from-sorted-array.java
@@ -0,0 +1,24 @@
+/*
+ * @lc app=leetcode id=26 lang=java
+ *
+ * [26] Remove Duplicates from Sorted Array
+ */
+
+// @lc code=start
+class Solution {
+    public int removeDuplicates(int[] nums) {
+        if(nums.length == 0) {
+            return 0;
+        }
+        int i = 0;
+        for(int j = 0; j< nums.length; j++) {
+            if(nums[j] != nums[i]) {
+                i++;
+                nums[i] = nums[j];
+            }
+        }
+        return i+1;
+    }
+}
+// @lc code=end
+
diff --git a/27.remove-element.java b/27.remove-element.java
new file mode 100644
index 0000000..a0d8079
--- /dev/null
+++ b/27.remove-element.java
@@ -0,0 +1,21 @@
+/*
+ * @lc app=leetcode id=27 lang=java
+ *
+ * [27] Remove Element
+ */
+
+// @lc code=start
+class Solution {
+    public int removeElement(int[] nums, int val) {
+        int i = 0;
+        for(int j = 0; j < nums.length; j++) {
+            if(nums[j] != val) {
+                nums[i] = nums[j];
+                i++;
+            }
+        }
+        return i;
+    }
+}
+// @lc code=end
+
diff --git a/28.find-the-index-of-the-first-occurrence-in-a-string.java b/28.find-the-index-of-the-first-occurrence-in-a-string.java
new file mode 100644
index 0000000..a69dbc8
--- /dev/null
+++ b/28.find-the-index-of-the-first-occurrence-in-a-string.java
@@ -0,0 +1,24 @@
+/*
+ * @lc app=leetcode id=28 lang=java
+ *
+ * [28] Find the Index of the First Occurrence in a String
+ */
+
+// @lc code=start
+class Solution {
+    public int strStr(String haystack, String needle) {
+        int idx = -1;
+        if(haystack.length() < needle.length()) {
+            return idx;
+        }
+        for(int i = 0; i < haystack.length(); i++) {
+            if(i + needle.length() <= haystack.length() && haystack.substring(i, i + needle.length()).equals(needle))  {
+                idx = i;
+                break;
+            }
+        }
+        return idx;
+    }
+}
+// @lc code=end
+
diff --git a/80.remove-duplicates-from-sorted-array-ii.java b/80.remove-duplicates-from-sorted-array-ii.java
new file mode 100644
index 0000000..9e9c053
--- /dev/null
+++ b/80.remove-duplicates-from-sorted-array-ii.java
@@ -0,0 +1,26 @@
+/*
+ * @lc app=leetcode id=80 lang=java
+ *
+ * [80] Remove Duplicates from Sorted Array II
+ */
+
+// @lc code=start
+class Solution {
+    public int removeDuplicates(int[] nums) {
+        int i = -1, freq = 0;
+        for(int j = 0; j< nums.length; j++) {
+            if(i<0 || nums[i] == nums[j] && freq < 2) {
+                i++;
+                nums[i] = nums[j];
+                freq++;
+            } else if(nums[i] != nums[j]) {
+                freq = 1;
+                i++;
+                nums[i] = nums[j];
+            }
+        }
+        return i+1;
+    }
+}
+// @lc code=end
+