diff --git a/longest-substring-without-repeating-characters/sangbeenmoon.py b/longest-substring-without-repeating-characters/sangbeenmoon.py
index eb2d80bd74..9350748911 100644
--- a/longest-substring-without-repeating-characters/sangbeenmoon.py
+++ b/longest-substring-without-repeating-characters/sangbeenmoon.py
@@ -14,3 +14,30 @@ def lengthOfLongestSubstring(self, s: str) -> int:
             answer = max(answer, i - start + 1)
             
         return answer
+
+
+# ------
+class Solution:
+    def lengthOfLongestSubstring(self, s: str) -> int:
+
+        left = 0
+        right = 0
+
+        answer = 0
+
+        dictionary = {}
+
+        for i,ch in enumerate(s):
+            right += 1
+            if ch not in dictionary:
+                dictionary[ch] = i
+            else:
+                idx = dictionary[ch]
+                if left <= idx:
+                    left = idx + 1
+                dictionary[ch] = i
+
+            print(right, left)
+            answer = max(answer, right - left)
+
+        return answer
diff --git a/number-of-islands/sangbeenmoon.py b/number-of-islands/sangbeenmoon.py
index 34b50b9a82..4f78b81065 100644
--- a/number-of-islands/sangbeenmoon.py
+++ b/number-of-islands/sangbeenmoon.py
@@ -27,3 +27,53 @@ def dfs(xx:int, yy:int):
                     answer = answer + 1
                     dfs(x,y)
         return answer
+
+# ------
+
+
+
+
+
+
+class Solution:
+    def numIslands(self, grid: List[List[str]]) -> int:
+
+        x_len , y_len = len(grid[0]), len(grid)
+
+        visited = [[False] * x_len for _ in range(y_len)]
+
+        dx = [0,0,-1,1]
+        dy = [-1,1,0,0]
+
+        def dfs(xx:int, yy:int):
+
+            for d in range(4):
+                nx = xx + dx[d]
+                ny = yy + dy[d]
+
+                if 0 <= nx and nx < x_len and 0 <= ny and ny < y_len and grid[ny][nx] == "1":
+                    if not visited[ny][nx]:
+                        visited[ny][nx] = True
+                        dfs(nx,ny)
+
+            return
+
+        answer = 0
+
+        for xx in range(x_len):
+            for yy in range(y_len):
+                if grid[yy][xx] == "1" and not visited[yy][xx]:
+                    answer += 1
+                    visited[yy][xx] = True
+                    dfs(xx,yy)
+
+        return answer
+
+
+                    
+
+            
+
+
+
+            
diff --git a/set-matrix-zeroes/sangbeenmoon.py b/set-matrix-zeroes/sangbeenmoon.py
index b4e010c14b..2070bfd9b2 100644
--- a/set-matrix-zeroes/sangbeenmoon.py
+++ b/set-matrix-zeroes/sangbeenmoon.py
@@ -20,3 +20,46 @@ def setZeroes(self, matrix: List[List[int]]) -> None:
             for c in range(n):
                 if r in row_dict or c in col_dict:
                     matrix[r][c] = 0
+
+
+
+
+
+
+
+
+
+# ---------
+
+# SC : O(1)
+
+class Solution:
+    def setZeroes(self, matrix: List[List[int]]) -> None:
+        """
+        Do not return anything, modify matrix in-place instead.
+        """
+        r_len , c_len = len(matrix), len(matrix[0])
+
+        set_zero_first_col = any(matrix[r][0] == 0 for r in range(r_len))
+
+        for r in range(r_len):
+            for c in range(1, c_len):   # c는 1부터
+                if matrix[r][c] == 0:
+                    matrix[r][0] = 0
+                    matrix[0][c] = 0
+
+        for r in range(1, r_len):
+            for c in range(1, c_len):
+                if matrix[r][0] == 0 or matrix[0][c] == 0:
+                    matrix[r][c] = 0        
+
+        if matrix[0][0] == 0:                  # 0행 먼저
+            for c in range(c_len):
+                matrix[0][c] = 0
+
+            
+        if set_zero_first_col:                 # 0열 나중
+            for r in range(r_len):
+                matrix[r][0] = 0         
+
+
diff --git a/unique-paths/sangbeenmoon.py b/unique-paths/sangbeenmoon.py
index e1907713e5..ae209fe167 100644
--- a/unique-paths/sangbeenmoon.py
+++ b/unique-paths/sangbeenmoon.py
@@ -11,3 +11,17 @@ def uniquePaths(self, m: int, n: int) -> int:
                 dp[r][c] = dp[r-1][c] + dp[r][c-1]
         
         return dp[m-1][n-1]
+
+
+
+# ------------
+
+class Solution:
+    def uniquePaths(self, m: int, n: int) -> int:
+        dp = [[1] * n for _ in range(m)]
+
+        for r in range(1,m):
+            for c in range(1,n):
+                dp[r][c] = dp[r-1][c] + dp[r][c-1]
+
+        return dp[m-1][n-1]