30. Substring with Concatenation of All Words

30. Substring with Concatenation of All Words/30. Substring with Concatenation of All Words.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <RootNamespace>_30._Substring_with_Concatenation_of_All_Words</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

30. Substring with Concatenation of All Words/Program.cs

@@ -0,0 +1,18 @@
+var sol = new Solution();
+
+var cases = new (string s, string[] words, int[] expected)[]
+{
+	// ("barfoothefoobarman", new[] { "foo", "bar" }, new[] { 0, 9 }),
+	// ("wordgoodgoodgoodbestword", new[] { "word", "good", "best", "word" }, Array.Empty<int>()),
+	// ("barfoofoobarthefoobarman", new[] { "bar", "foo", "the" }, new[] { 6, 9, 12 }),
+	("wordgoodgoodgoodbestword", new[] { "word", "good", "best", "good" }, new[] { 8 })
+};
+
+string Format(IEnumerable<int> values) => $"[{string.Join(",", values)}]";
+string FormatWords(IEnumerable<string> values) => $"[{string.Join(",", values)}]";
+
+foreach (var (s, words, expected) in cases)
+{
+	var actual = sol.FindSubstring(s, words);
+	Console.WriteLine($"{s} | {FormatWords(words)} -> {Format(actual)} (expected: {Format(expected)})");
+}

30. Substring with Concatenation of All Words/Solution.cs

@@ -0,0 +1,36 @@
+public class Solution {
+    public IList<int> FindSubstring(string s, string[] words) {
+        var len = words[0].Length;
+        var allLen = len*words.Length;
+        var dict = new Dictionary<string, int>();
+        foreach(var word in words)
+        {
+            dict.TryAdd(word, 0);
+            dict[word]++;
+        }
+        var answer = new List<int>();
+        var dictClone = new Dictionary<string, int>(dict);
+        for(var i = 0; i < s.Length-allLen+1; i++)
+        {
+            var valid = 0;
+            foreach (var kvp in dictClone)
+                dictClone[kvp.Key] = dict[kvp.Key];
+            for(var j=i; j < i+allLen; j+=len)
+            {
+                var word = s[j..(j+len)];
+                if(dictClone.TryGetValue(word, out var count) && count > 0)
+                {
+                    dictClone[word]--;
+                    valid++;
+                }
+                else
+                {
+                    break;
+                }
+            }
+            if(valid == words.Length)
+                answer.Add(i);
+        }
+        return answer;
+    }
+}