Solve LeetCode #14 'Longest Common Prefix' [Easy].

LeetCode/src/LeetCode.Challenges/Problems0XX/P014_LongestCommonPrefix/Solution.cs

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+namespace LeetCode.Challenges.Problems0XX.P014_LongestCommonPrefix;
+
+public static class Solution
+{
+    // Explanation:
+    // 1. If the input array is null or empty, return an empty string, as there's no prefix to find.
+    // 2. Use the first string in the array as the initial prefix.
+    // 3. For each subsequent string in the array:
+    //    -- Check if it starts with the current prefix.
+    //    -- If it does not, remove the last character from the prefix and recheck.
+    //    -- Repeat this until the prefix matches the start of the current string or becomes empty.
+    // 4. If at any point the prefix becomes empty, return an empty string (no common prefix exists).
+    // 5. After all strings are processed, the prefix will contain the longest common prefix.
+    public static string LongestCommonPrefix(string[] strings)
+    {
+        if (strings == null! || strings.Length == 0)
+        {
+            return string.Empty;
+        }
+
+        var prefix = strings[0];
+        for (var i = 1; i < strings.Length; i++)
+        {
+            while (!strings[i].StartsWith(prefix))
+            {
+                prefix = prefix.Substring(0, prefix.Length - 1);
+                if (string.IsNullOrEmpty(prefix))
+                {
+                    return string.Empty;
+                }
+            }
+        }
+
+        return prefix;
+    }
+}

LeetCode/tests/LeetCode.Challenges.UnitTests/Problems0XX/P014_LongestCommonPrefix/SolutionTests.cs

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+using LeetCode.Challenges.Problems0XX.P014_LongestCommonPrefix;
+using Shouldly;
+using Xunit;
+
+namespace LeetCode.Challenges.UnitTests.Problems0XX.P014_LongestCommonPrefix;
+
+public class SolutionTests
+{
+    [Theory]
+    [MemberData(nameof(TestData))]
+    public void GivenStrings_WhenLongestCommonPrefix_ThenResultAsExpected(
+        string[] strings, string expectedResult)
+    {
+        Solution.LongestCommonPrefix(strings).ShouldBe(expectedResult);
+    }
+
+    public static IEnumerable<object[]> TestData()
+    {
+        yield return [new[] { "abcd", "abcef", "abcxy" }, "abc"];
+        yield return [new[] { "flower", "flow", "flight" }, "fl"];
+        yield return [new[] { "dog", "racecar", "car" }, ""];
+        yield return [new[] { "apple" }, "apple"];
+        yield return [new[] { "a", "a", "a" }, "a"];
+        yield return [new[] { "abc", "abcd", "ab" }, "ab"];
+        yield return [new[] { "prefix", "preach", "prevent" }, "pre"];
+        yield return [new[] { "xylophone", "xylene", "xylitol" }, "xyl"];
+        yield return [new[] { "banana", "band", "banter" }, "ban"];
+        yield return [new[] { "hello", "world" }, ""];
+        yield return [Array.Empty<string>(), ""];
+    }
+}