From ae60758078fbf96b6103aad59173b379e46228bf Mon Sep 17 00:00:00 2001
From: kimseongeun <sekim520@gmail.com>
Date: Mon, 28 Apr 2025 15:11:57 +0900
Subject: [PATCH 1/3] week 5 solution

---
 best-time-to-buy-and-sell-stock/i-mprovising.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 best-time-to-buy-and-sell-stock/i-mprovising.py

diff --git a/best-time-to-buy-and-sell-stock/i-mprovising.py b/best-time-to-buy-and-sell-stock/i-mprovising.py
new file mode 100644
index 000000000..7c24c5036
--- /dev/null
+++ b/best-time-to-buy-and-sell-stock/i-mprovising.py
@@ -0,0 +1,16 @@
+"""
+Time complexity O(n)
+Space complexity O(1)
+
+Dynamic programming
+"""
+
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+        max_profit = 0
+        min_price = prices[0]
+        for p in prices:
+            max_profit = max(max_profit, p - min_price)
+            min_price = min(min_price, p)
+
+        return max_profit
\ No newline at end of file

From 86d583192e3f38075ced006efa17f08c38c39fad Mon Sep 17 00:00:00 2001
From: kimseongeun <sekim520@gmail.com>
Date: Tue, 29 Apr 2025 15:10:34 +0900
Subject: [PATCH 2/3] week 5 solutions

---
 .../i-mprovising.py                           |  2 +-
 group-anagrams/i-mprovising.py                | 15 +++++++
 implement-trie-prefix-tree/i-mprovising.py    | 39 +++++++++++++++++++
 word-break/i-mprovising.py                    | 27 +++++++++++++
 4 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 group-anagrams/i-mprovising.py
 create mode 100644 implement-trie-prefix-tree/i-mprovising.py
 create mode 100644 word-break/i-mprovising.py

diff --git a/best-time-to-buy-and-sell-stock/i-mprovising.py b/best-time-to-buy-and-sell-stock/i-mprovising.py
index 7c24c5036..9085c0207 100644
--- a/best-time-to-buy-and-sell-stock/i-mprovising.py
+++ b/best-time-to-buy-and-sell-stock/i-mprovising.py
@@ -13,4 +13,4 @@ def maxProfit(self, prices: List[int]) -> int:
             max_profit = max(max_profit, p - min_price)
             min_price = min(min_price, p)
 
-        return max_profit
\ No newline at end of file
+        return max_profit
diff --git a/group-anagrams/i-mprovising.py b/group-anagrams/i-mprovising.py
new file mode 100644
index 000000000..2af3ecaf4
--- /dev/null
+++ b/group-anagrams/i-mprovising.py
@@ -0,0 +1,15 @@
+"""
+Time complexity O(n)
+Space compexity O(n)
+
+hash table, sorting
+"""
+
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        group = defaultdict(list)
+        for s in strs:
+            sorted_str = str(sorted(s))
+            group[sorted_str].append(s)
+        
+        return list(group.values())
diff --git a/implement-trie-prefix-tree/i-mprovising.py b/implement-trie-prefix-tree/i-mprovising.py
new file mode 100644
index 000000000..dd555e5d1
--- /dev/null
+++ b/implement-trie-prefix-tree/i-mprovising.py
@@ -0,0 +1,39 @@
+"""
+Time complexity O(n)
+"""
+
+class Node:
+    def __init__(self, end=False):
+        self.children = {} # hash table
+        self.end = end
+
+class Trie:
+    def __init__(self):
+        self.root = Node(end=True)
+
+    def insert(self, word: str) -> None:
+        node = self.root
+        
+        for c in word:
+            if c not in node.children:
+                node.children[c] = Node()
+            node = node.children[c]
+        node.end = True
+        
+    def search(self, word: str) -> bool:
+        node = self.root
+        for c in word:
+            if c not in node.children:
+                return False
+            node = node.children[c]
+        if node.end:
+            return True
+        return False
+
+    def startsWith(self, prefix: str) -> bool:
+        node = self.root
+        for c in prefix:
+            if c not in node.children:
+                return False
+            node = node.children[c]
+        return True
diff --git a/word-break/i-mprovising.py b/word-break/i-mprovising.py
new file mode 100644
index 000000000..ebf939215
--- /dev/null
+++ b/word-break/i-mprovising.py
@@ -0,0 +1,27 @@
+"""
+Time complexity O(n*m) n: len(s), m:len(wordDict)
+Space compexity O(n)
+
+dynamic programming
+"""
+
+class Solution:
+    def wordBreak(self, s: str, wordDict: List[str]) -> bool:
+        dp = [False for _ in range(len(s))]
+        for i in range(len(s)):
+            flag = False
+            for word in wordDict:
+                n = len(word)
+                if i - n + 1 < 0:
+                    continue
+                if s[i-n+1:i+1] != word:
+                    continue
+                if i - n + 1 == 0:
+                    flag = True
+                    break
+                elif i - n + 1 > 0:
+                    if dp[i - n]:
+                        flag = True
+                        break
+            dp[i] = flag
+        return dp[-1]

From c8051cb2d8a979e86977e17a0f6982d0dc984d84 Mon Sep 17 00:00:00 2001
From: kimseongeun <sekim520@gmail.com>
Date: Fri, 2 May 2025 17:14:50 +0900
Subject: [PATCH 3/3] fix group-anagrams time comlexity

---
 group-anagrams/i-mprovising.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/group-anagrams/i-mprovising.py b/group-anagrams/i-mprovising.py
index 2af3ecaf4..6f1d036be 100644
--- a/group-anagrams/i-mprovising.py
+++ b/group-anagrams/i-mprovising.py
@@ -1,5 +1,9 @@
 """
 Time complexity O(n)
+--> O(n * wlog(w))
+n : 주어지는 단어 개수
+w : 평균 단어 길이
+
 Space compexity O(n)
 
 hash table, sorting