test: add leetcode 2185 with tests, complexity docs, and migration

README.md

@@ -44,11 +44,11 @@ Each problem follows this structure:
 
 ## Solutions
 
-📊 **Statistics**: 52 problems solved (migrated to new structure)
+📊 **Statistics**: 53 problems solved (migrated to new structure)
 
 | Difficulty | Count |
 |------------|-------|
-| Easy       | 36    |
+| Easy       | 37    |
 | Medium     | 15    |
 | Hard       | 1     |
 

docs/EASY.md

@@ -1,6 +1,6 @@
 # Easy Problems
 
-Total: 36 problems solved
+Total: 37 problems solved
 
 ## Solutions
 
@@ -37,6 +37,7 @@ Total: 36 problems solved
 | 2011 | [Final Value of Variable After Performing Operations](https://leetcode.com/problems/final-value-of-variable-after-performing-operations/) | [FinalValueOfVariableAfterPerformingOperations2011.java](../src/main/java/com/leetcode/easy/FinalValueOfVariableAfterPerformingOperations2011.java) | [FinalValueOfVariableAfterPerformingOperations2011Test.java](../src/test/java/com/leetcode/easy/FinalValueOfVariableAfterPerformingOperations2011Test.java) |
 | 2032 | [Two Out of Three](https://leetcode.com/problems/two-out-of-three/) | [TwoOutOfThree2032.java](../src/main/java/com/leetcode/easy/TwoOutOfThree2032.java) | [TwoOutOfThree2032Test.java](../src/test/java/com/leetcode/easy/TwoOutOfThree2032Test.java) |
 | 2124 | [Check if All A's Appears Before All B's](https://leetcode.com/problems/check-if-all-as-appears-before-all-bs/) | [CheckIfAllAsAppearsBeforeAllBs2124.java](../src/main/java/com/leetcode/easy/CheckIfAllAsAppearsBeforeAllBs2124.java) | [CheckIfAllAsAppearsBeforeAllBs2124Test.java](../src/test/java/com/leetcode/easy/CheckIfAllAsAppearsBeforeAllBs2124Test.java) |
+| 2185 | [Counting Words With a Given Prefix](https://leetcode.com/problems/counting-words-with-a-given-prefix/) | [CountingWordsWithAGivenPrefix2185.java](../src/main/java/com/leetcode/easy/CountingWordsWithAGivenPrefix2185.java) | [CountingWordsWithAGivenPrefix2185Test.java](../src/test/java/com/leetcode/easy/CountingWordsWithAGivenPrefix2185Test.java) |
 | 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) |

src/main/java/com/leetcode/easy/CountingWordsWithAGivenPrefix2185.java

@@ -0,0 +1,37 @@
+// Tags: Array, String
+package com.leetcode.easy;
+
+public class CountingWordsWithAGivenPrefix2185 {
+    /**
+     * Returns the number of strings in the array that have the given prefix.
+     *
+     * <p>This method iterates through each word in the array and checks if it starts
+     * with the specified prefix using String.startsWith().
+     *
+     * @param words the array of strings to search through
+     * @param pref the prefix string to match
+     * @return the count of words that start with the given prefix
+     *
+     * <p><b>Time Complexity:</b> O(n * m)
+     * <ul>
+     *   <li>n = number of words in the array</li>
+     *   <li>m = length of the prefix string</li>
+     *   <li>We iterate through n words, and for each word, startsWith() compares up to m characters</li>
+     * </ul>
+     *
+     * <p><b>Space Complexity:</b> O(1)
+     * <ul>
+     *   <li>Only uses a constant amount of extra space (the result counter variable)</li>
+     *   <li>No data structures that scale with input size</li>
+     * </ul>
+     */
+    public int prefixCount(String[] words, String pref) {
+        int res = 0;
+        for (String word : words) {
+            if (word.startsWith(pref)) {
+                res += 1;
+            }
+        }
+        return res;
+    }
+}

src/test/java/com/leetcode/easy/CountingWordsWithAGivenPrefix2185Test.java

@@ -0,0 +1,41 @@
+package com.leetcode.easy;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class CountingWordsWithAGivenPrefix2185Test {
+    private CountingWordsWithAGivenPrefix2185 solution;
+
+    @BeforeEach
+    void setUp() {
+        solution = new CountingWordsWithAGivenPrefix2185();
+    }
+
+    @Test
+    void testPrefixCount_Example1_TwoMatches() {
+        // Input: words = ["pay","attention","practice","attend"], pref = "at"
+        // Output: 2
+        // Explanation: The 2 strings that contain "at" as a prefix are: "attention" and "attend".
+        String[] words = {"pay", "attention", "practice", "attend"};
+        String pref = "at";
+
+        int result = solution.prefixCount(words, pref);
+
+        assertEquals(2, result);
+    }
+
+    @Test
+    void testPrefixCount_Example2_NoMatches() {
+        // Input: words = ["leetcode","win","loops","success"], pref = "code"
+        // Output: 0
+        // Explanation: There are no strings that contain "code" as a prefix.
+        String[] words = {"leetcode", "win", "loops", "success"};
+        String pref = "code";
+
+        int result = solution.prefixCount(words, pref);
+
+        assertEquals(0, result);
+    }
+}