From 6595d65048fa0d86594dda17c84a1c971e14b11f Mon Sep 17 00:00:00 2001
From: Peter Chen <sanpeter992000@gmail.com>
Date: Tue, 31 Mar 2026 19:40:40 +0800
Subject: [PATCH] feat: add leetcode 2828 - check if a string is an acronym of
 words

  Add implementation for LeetCode problem 2828 with:
  - O(n) time complexity solution using StringBuilder
  - Comprehensive Javadoc with complexity analysis
  - Documentation updates (README.md and docs/EASY.md)
---
 README.md                                     |  4 +-
 docs/EASY.md                                  |  3 +-
 src/CheckIfAStringIsAnAcronymOfWords2828.java | 22 ----------
 .../CheckIfAStringIsAnAcronymOfWords2828.java | 40 +++++++++++++++++++
 4 files changed, 44 insertions(+), 25 deletions(-)
 delete mode 100644 src/CheckIfAStringIsAnAcronymOfWords2828.java
 create mode 100644 src/main/java/com/leetcode/easy/CheckIfAStringIsAnAcronymOfWords2828.java

diff --git a/README.md b/README.md
index 6e40833..b5bffd7 100644
--- a/README.md
+++ b/README.md
@@ -44,11 +44,11 @@ Each problem follows this structure:
 
 ## Solutions
 
-📊 **Statistics**: 51 problems solved (migrated to new structure)
+📊 **Statistics**: 52 problems solved (migrated to new structure)
 
 | Difficulty | Count |
 |------------|-------|
-| Easy       | 35    |
+| Easy       | 36    |
 | Medium     | 15    |
 | Hard       | 1     |
 
diff --git a/docs/EASY.md b/docs/EASY.md
index a3ac856..37bda59 100644
--- a/docs/EASY.md
+++ b/docs/EASY.md
@@ -1,6 +1,6 @@
 # Easy Problems
 
-Total: 35 problems solved
+Total: 36 problems solved
 
 ## Solutions
 
@@ -40,6 +40,7 @@ Total: 35 problems solved
 | 2315 | [Count Asterisks](https://leetcode.com/problems/count-asterisks/) | [CountAsterisks2315.java](../src/main/java/com/leetcode/easy/CountAsterisks2315.java) | [CountAsterisks2315Test.java](../src/test/java/com/leetcode/easy/CountAsterisks2315Test.java) |
 | 2469 | [Convert the Temperature](https://leetcode.com/problems/convert-the-temperature/) | [ConvertTheTemperature2469.java](../src/main/java/com/leetcode/easy/ConvertTheTemperature2469.java) | [ConvertTheTemperature2469Test.java](../src/test/java/com/leetcode/easy/ConvertTheTemperature2469Test.java) |
 | 2798 | [Number of Employees Who Met the Target](https://leetcode.com/problems/number-of-employees-who-met-the-target/) | [NumberOfEmployeesWhoMetTheTarget2798.java](../src/main/java/com/leetcode/easy/NumberOfEmployeesWhoMetTheTarget2798.java) | [NumberOfEmployeesWhoMetTheTarget2798Test.java](../src/test/java/com/leetcode/easy/NumberOfEmployeesWhoMetTheTarget2798Test.java) |
+| 2828 | [Check If A String Is An Acronym Of Words](https://leetcode.com/problems/check-if-a-string-is-an-acronym-of-words/) | [CheckIfAStringIsAnAcronymOfWords2828.java](../src/main/java/com/leetcode/easy/CheckIfAStringIsAnAcronymOfWords2828.java) | |
 | 3289 | [The Two Sneaky Numbers of Digitville](https://leetcode.com/problems/the-two-sneaky-numbers-of-digitville/) | [TheTwoSneakyNumbersOfDigitville3289.java](../src/main/java/com/leetcode/easy/TheTwoSneakyNumbersOfDigitville3289.java) | [TheTwoSneakyNumbersOfDigitville3289Test.java](../src/test/java/com/leetcode/easy/TheTwoSneakyNumbersOfDigitville3289Test.java) |
 
 ---
diff --git a/src/CheckIfAStringIsAnAcronymOfWords2828.java b/src/CheckIfAStringIsAnAcronymOfWords2828.java
deleted file mode 100644
index 62c8ac1..0000000
--- a/src/CheckIfAStringIsAnAcronymOfWords2828.java
+++ /dev/null
@@ -1,22 +0,0 @@
-import java.util.ArrayList;
-import java.util.List;
-
-public class CheckIfAStringIsAnAcronymOfWords2828 {
-    public boolean isAcronym(List<String> words, String s) {
-        String acronym = "";
-        for (String word : words) {
-            char[] chars = word.toCharArray();
-            acronym += chars[0];
-        }
-        return acronym.equals(s);
-    }
-
-    public static void main(String[] args) {
-        List<String> words = new ArrayList<>();
-        words.add("alice");
-        words.add("bob");
-        words.add("charlie");
-        String s = "abc";
-        assert new CheckIfAStringIsAnAcronymOfWords2828().isAcronym(words, s);
-    }
-}
diff --git a/src/main/java/com/leetcode/easy/CheckIfAStringIsAnAcronymOfWords2828.java b/src/main/java/com/leetcode/easy/CheckIfAStringIsAnAcronymOfWords2828.java
new file mode 100644
index 0000000..343ae61
--- /dev/null
+++ b/src/main/java/com/leetcode/easy/CheckIfAStringIsAnAcronymOfWords2828.java
@@ -0,0 +1,40 @@
+// Tags: Array, String
+package com.leetcode.easy;
+
+import java.util.List;
+
+public class CheckIfAStringIsAnAcronymOfWords2828 {
+    /**
+     * Checks if a string is an acronym of the given list of words.
+     * <p>
+     * An acronym is formed by taking the first character of each word
+     * and concatenating them in order.
+     * <p>
+     * <b>Time Complexity: O(n)</b>
+     * <ul>
+     *   <li>n = number of words in the list</li>
+     *   <li>Size comparison check: O(1)</li>
+     *   <li>Single pass through words list: O(n)</li>
+     *   <li>String comparison: O(n)</li>
+     * </ul>
+     * <p>
+     * <b>Space Complexity: O(n)</b>
+     * <ul>
+     *   <li>StringBuilder stores n characters: O(n)</li>
+     * </ul>
+     *
+     * @param words list of non-empty strings
+     * @param s     the string to check if it's the acronym
+     * @return {@code true} if s is the acronym of words, {@code false} otherwise
+     */
+    public boolean isAcronym(List<String> words, String s) {
+        if (words.size() != s.length()) {
+            return false;
+        }
+        StringBuilder sb = new StringBuilder();
+        for (String word : words) {
+            sb.append(word.charAt(0));
+        }
+        return sb.toString().equals(s);
+    }
+}