diff --git a/container-with-most-water/yuseok89.py b/container-with-most-water/yuseok89.py
new file mode 100644
index 0000000000..2938344e63
--- /dev/null
+++ b/container-with-most-water/yuseok89.py
@@ -0,0 +1,22 @@
+# TC: O(N)
+# SC: O(1)
+class Solution:
+    def maxArea(self, height: List[int]) -> int:
+        l = 0
+        r = len(height) - 1
+        max_height = max(height)
+        ans = 0
+
+        while l < r:
+            ans = max(ans, min(height[l], height[r]) * (r - l))
+
+            if ans > max_height * (r - l):
+                return ans
+
+            if height[l] < height[r]:
+                l += 1
+            else:
+                r -= 1
+
+        return ans
+
diff --git a/design-add-and-search-words-data-structure/yuseok89.py b/design-add-and-search-words-data-structure/yuseok89.py
new file mode 100644
index 0000000000..c7989240f3
--- /dev/null
+++ b/design-add-and-search-words-data-structure/yuseok89.py
@@ -0,0 +1,38 @@
+class WordDictionary:
+
+    def __init__(self):
+        self.trie = {}
+
+    def addWord(self, word: str) -> None:
+        cur = self.trie
+
+        for c in word:
+            if c not in cur:
+                cur[c] = {}
+            cur = cur[c]
+
+        cur[0] = True
+
+    def search(self, word: str) -> bool:
+
+        n = len(word)
+
+        def rec(cur: dict, idx: int) -> bool:
+            if idx == n:
+                return 0 in cur
+
+            if word[idx] == '.':
+                for next in cur:
+                    if next == 0:
+                        continue
+                    if rec(cur[next], idx + 1):
+                        return True
+                return False
+            else:
+                if word[idx] in cur:
+                    return rec(cur[word[idx]], idx + 1)
+                else:
+                    return False
+
+        return rec(self.trie, 0)
+
diff --git a/longest-increasing-subsequence/yuseok89.py b/longest-increasing-subsequence/yuseok89.py
new file mode 100644
index 0000000000..1493180e19
--- /dev/null
+++ b/longest-increasing-subsequence/yuseok89.py
@@ -0,0 +1,15 @@
+# TC: O(NlogN)
+# SC: O(N)
+class Solution:
+    def lengthOfLIS(self, nums: List[int]) -> int:
+        arr = []
+
+        for num in nums:
+            if len(arr) == 0 or arr[-1] < num:
+                arr.append(num)
+            else:
+                idx = bisect_left(arr, num)
+                arr[idx] = num
+
+        return len(arr)
+
diff --git a/spiral-matrix/yuseok89.py b/spiral-matrix/yuseok89.py
new file mode 100644
index 0000000000..06c9f827f0
--- /dev/null
+++ b/spiral-matrix/yuseok89.py
@@ -0,0 +1,26 @@
+# TC: O(N*M)
+# SC: O(N*M)
+class Solution:
+    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
+        n = len(matrix)
+        m = len(matrix[0])
+        ans = []
+        row, col, dir = 0, -1, 1
+
+        n -= 1
+
+        while n >= 0 and m >= 1:
+            for i in range(0, m):
+                col += dir
+                ans.append(matrix[row][col])
+
+            for i in range(0, n):
+                row += dir
+                ans.append(matrix[row][col])
+
+            n -= 1
+            m -= 1
+            dir *= -1
+
+        return ans;
+
diff --git a/valid-parentheses/yuseok89.py b/valid-parentheses/yuseok89.py
new file mode 100644
index 0000000000..fffc7ebeb4
--- /dev/null
+++ b/valid-parentheses/yuseok89.py
@@ -0,0 +1,16 @@
+# TC: O(N)
+# SC: O(N)
+class Solution:
+    def isValid(self, s: str) -> bool:
+        pars = {'(': ')', '{': '}', '[': ']'}
+        stack = []
+
+        for c in s:
+            if c in pars:
+                stack.append(c)
+            else:
+                if not stack or pars[stack.pop()] != c:
+                    return False
+
+        return len(stack) == 0
+