From 81a5acb83d1763966fec8ffa960a64e1377cb396 Mon Sep 17 00:00:00 2001
From: casentino <opterk@gmail.com>
Date: Fri, 12 Dec 2025 23:16:26 +0900
Subject: [PATCH 1/4] Best Time to Buy and Sell Stock

---
 best-time-to-buy-and-sell-stock/casentino.ts | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 best-time-to-buy-and-sell-stock/casentino.ts

diff --git a/best-time-to-buy-and-sell-stock/casentino.ts b/best-time-to-buy-and-sell-stock/casentino.ts
new file mode 100644
index 0000000000..d6ef6361c9
--- /dev/null
+++ b/best-time-to-buy-and-sell-stock/casentino.ts
@@ -0,0 +1,11 @@
+function maxProfit(prices: number[]): number {
+  const dp = new Array(prices.length).fill(0);
+  dp[0] = 0;
+  let maxProfit = 0;
+  for (let i = 1; i < prices.length; i++) {
+    dp[i] = Math.max(prices[i] - prices[i - 1], prices[i] - prices[i - 1] + dp[i - 1]);
+
+    maxProfit = Math.max(dp[i], maxProfit);
+  }
+  return maxProfit;
+}

From e09e5877184c2a252eab47fb863964ab9146f3b5 Mon Sep 17 00:00:00 2001
From: casentino <opterk@gmail.com>
Date: Fri, 12 Dec 2025 23:17:08 +0900
Subject: [PATCH 2/4] Group Anagram

---
 group-anagrams/casentino.ts | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 group-anagrams/casentino.ts

diff --git a/group-anagrams/casentino.ts b/group-anagrams/casentino.ts
new file mode 100644
index 0000000000..40e5e3b4fe
--- /dev/null
+++ b/group-anagrams/casentino.ts
@@ -0,0 +1,13 @@
+function groupAnagrams(strs: string[]): string[][] {
+  const hashMap = new Map();
+  for (let i = 0; i < strs.length; i++) {
+    const key = Array.from(strs[i]).sort().join("");
+
+    if (!hashMap.has(key)) {
+      hashMap.set(key, [strs[i]]);
+    } else {
+      hashMap.get(key).push(strs[i]);
+    }
+  }
+  return Array.from(hashMap.values());
+}

From 04a6a59fa77051197fe5aa6f5b7b5f14c985f1cd Mon Sep 17 00:00:00 2001
From: casentino <opterk@gmail.com>
Date: Fri, 12 Dec 2025 23:18:25 +0900
Subject: [PATCH 3/4] Implement Trie (Prefix Tree)

---
 implement-trie-prefix-tree/casentino.ts | 55 +++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 implement-trie-prefix-tree/casentino.ts

diff --git a/implement-trie-prefix-tree/casentino.ts b/implement-trie-prefix-tree/casentino.ts
new file mode 100644
index 0000000000..f17ebe70bd
--- /dev/null
+++ b/implement-trie-prefix-tree/casentino.ts
@@ -0,0 +1,55 @@
+type ChildTrie = {
+  value?: string;
+  isEnd?: boolean;
+  childrens: ChildrenMap;
+};
+type ChildrenMap = {
+  [key: string]: ChildTrie;
+};
+
+class Trie {
+  childrens: ChildrenMap = {};
+  constructor() {}
+
+  insert(word: string): void {
+    if (word.length === 0) {
+      return;
+    }
+    let current: ChildTrie = {
+      childrens: this.childrens,
+    };
+    for (let i = 0; i < word.length; i++) {
+      if (current.childrens[word[i]] === undefined) {
+        current.childrens[word[i]] = { value: word[i], isEnd: false, childrens: {} };
+      }
+
+      current = current.childrens[word[i]];
+    }
+    current.isEnd = true;
+  }
+
+  search(word: string): boolean {
+    let current: ChildTrie = {
+      childrens: this.childrens,
+    };
+    for (let i = 0; i < word.length; i++) {
+      if (current.childrens[word[i]] === undefined) {
+        return false;
+      }
+
+      current = current.childrens[word[i]];
+    }
+    return current.isEnd ?? false;
+  }
+
+  startsWith(prefix: string): boolean {
+    let current = this.childrens;
+    for (let i = 0; i < prefix.length; i++) {
+      if (current[prefix[i]] === undefined) {
+        return false;
+      }
+      current = current[prefix[i]].childrens;
+    }
+    return true;
+  }
+}

From 2c831f667115bcb773085f365851508b09d15892 Mon Sep 17 00:00:00 2001
From: casentino <opterk@gmail.com>
Date: Fri, 12 Dec 2025 23:19:05 +0900
Subject: [PATCH 4/4] Word Break

---
 word-break/casentino.ts | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 word-break/casentino.ts

diff --git a/word-break/casentino.ts b/word-break/casentino.ts
new file mode 100644
index 0000000000..e6677e0700
--- /dev/null
+++ b/word-break/casentino.ts
@@ -0,0 +1,15 @@
+function wordBreak(s: string, wordDict: string[]): boolean {
+  const dp = new Array(s.length + 1).fill(false);
+  dp[0] = true;
+  for (let i = 1; i <= s.length; i++) {
+    let str = "";
+    for (let j = 0; j < wordDict.length; j++) {
+      let start = i - wordDict[j].length;
+      if (start >= 0 && dp[start] && s.substring(start, i) === wordDict[j]) {
+        dp[i] = true;
+        break;
+      }
+    }
+  }
+  return dp[s.length];
+}