diff --git a/container-with-most-water/daehyun99.py b/container-with-most-water/daehyun99.py
new file mode 100644
index 0000000000..2a086277ee
--- /dev/null
+++ b/container-with-most-water/daehyun99.py
@@ -0,0 +1,18 @@
+# Time: O(N)
+# Space: O(1)
+class Solution:
+    def maxArea(self, height: List[int]) -> int:
+        size = 0
+        l, r = 0, len(height)-1
+        length = len(height)-1
+
+        while l < r:
+            if height[l] < height[r]:
+                size = max(size, height[l] * length)
+                l += 1
+                length -= 1
+            else:
+                size = max(size, height[r] * length)
+                r -= 1
+                length -= 1
+        return size
diff --git a/design-add-and-search-words-data-structure/daehyun99.py b/design-add-and-search-words-data-structure/daehyun99.py
new file mode 100644
index 0000000000..6c105daf4a
--- /dev/null
+++ b/design-add-and-search-words-data-structure/daehyun99.py
@@ -0,0 +1,39 @@
+class WordDictionary:
+
+    def __init__(self):
+        self.root = {}
+        
+    def addWord(self, word: str) -> None:
+        pointer = self.root
+        for char in word:
+            if char in pointer:
+                pointer = pointer[char]
+            else:
+                pointer[char] = {}
+                pointer = pointer[char]
+        pointer["0"]={}
+
+    def search(self, word: str) -> bool:
+        from collections import deque
+        pointer = self.root
+        que = deque()
+        que.append(pointer)
+
+        for char in word:
+            for i in range(len(que)):
+                pointer = que.popleft()
+                if char in pointer:
+                    que.append(pointer[char])
+                elif char == ".":
+                    for key in pointer.keys():
+                        que.append(pointer[key])
+        while len(que) > 0:
+            pointer = que.popleft()
+            if "0" in pointer:
+                return True
+        return False
+
+# Your WordDictionary object will be instantiated and called as such:
+# obj = WordDictionary()
+# obj.addWord(word)
+# param_2 = obj.search(word)
diff --git a/longest-increasing-subsequence/daehyun99.py b/longest-increasing-subsequence/daehyun99.py
new file mode 100644
index 0000000000..af00231962
--- /dev/null
+++ b/longest-increasing-subsequence/daehyun99.py
@@ -0,0 +1,11 @@
+# Time: O(N**2)
+# Space: O(N)
+class Solution:
+    def lengthOfLIS(self, nums: List[int]) -> int:
+        counts = [1 for i in nums]
+
+        for i in range(1, len(nums)):
+            for j in range(0, i):
+                if nums[j] < nums[i]:
+                    counts[i] = max(counts[i], counts[j]+1)
+        return max(counts)
diff --git a/spiral-matrix/daehyun99.py b/spiral-matrix/daehyun99.py
new file mode 100644
index 0000000000..c9ec0e3e72
--- /dev/null
+++ b/spiral-matrix/daehyun99.py
@@ -0,0 +1,55 @@
+class Solution:
+    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
+        height = len(matrix)
+        weight = len(matrix[0])
+        adding = [
+            [0, 1],
+            [1, 0],
+            [0, -1],
+            [-1, 0]
+        ]
+        m = 0
+        n = -1
+        size = height * weight
+        count = 0
+
+        result = []
+        
+        while count < size:
+            if 0 < weight and count < size:
+                m_add, n_add = adding[0]
+                for _ in range(weight):
+                    m += m_add
+                    n += n_add
+                    result.append(matrix[m][n])
+                    count += 1
+
+            height -= 1
+            if 0 < height and count < size:
+                m_add, n_add = adding[1]
+                for _ in range(height):
+                    m += m_add
+                    n += n_add
+                    result.append(matrix[m][n])
+                    count += 1
+
+            weight -= 1
+            if 0 < weight and count < size:
+                m_add, n_add = adding[2]
+                for _ in range(weight):
+                    m += m_add
+                    n += n_add
+                    result.append(matrix[m][n])
+                    count += 1
+            
+            height -= 1
+            if 0 < height and count < size:
+                m_add, n_add = adding[3]
+                for _ in range(height):
+                    m += m_add
+                    n += n_add
+                    result.append(matrix[m][n])
+                    count += 1
+
+            weight -= 1
+        return result
diff --git a/valid-parentheses/daehyun99.py b/valid-parentheses/daehyun99.py
new file mode 100644
index 0000000000..084b06699a
--- /dev/null
+++ b/valid-parentheses/daehyun99.py
@@ -0,0 +1,16 @@
+class Solution:
+    def isValid(self, s: str) -> bool:
+        stack = []
+
+        map = {"()", "{}", "[]"}
+
+        for char in s:
+            stack.append(char)
+            if len(stack) >= 2:
+                if ''.join(stack[-2:]) in map:
+                    stack.pop()
+                    stack.pop()
+        if len(stack) == 0:
+            return True
+        else:
+            return False