diff --git "a/leetcode3/\353\263\200\354\247\200\355\230\221/v3/125. Valid Palindrome.py" "b/leetcode3/\353\263\200\354\247\200\355\230\221/v3/125. Valid Palindrome.py"
new file mode 100644
index 00000000..4f54113c
--- /dev/null
+++ "b/leetcode3/\353\263\200\354\247\200\355\230\221/v3/125. Valid Palindrome.py"	
@@ -0,0 +1,30 @@
+'''
+1. 아이디어 :
+- 문자열을 정제한 후, 정제된 문자열이 회문인지 확인.
+2. 시간복잡도 :
+o(n)
+3. 자료구조/알고리즘 :
+
+'''
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        small = 'abcdefghijklmnopqrstuvwxyz'
+        big = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+
+        dic = {}
+        
+        for i in range(26):
+            dic[small[i]] = small[i]
+            dic[big[i]] = small[i]
+        
+        for i in '0123456789':
+            dic[i] = i
+
+        refined = ''
+        for i in s:
+            if i in dic:
+                refined += dic[i]
+        
+        print(refined)
+
+        return refined == refined[::-1]
\ No newline at end of file
diff --git "a/leetcode3/\353\263\200\354\247\200\355\230\221/v3/447. Number of Boomerangs.py" "b/leetcode3/\353\263\200\354\247\200\355\230\221/v3/447. Number of Boomerangs.py"
new file mode 100644
index 00000000..7c1481d3
--- /dev/null
+++ "b/leetcode3/\353\263\200\354\247\200\355\230\221/v3/447. Number of Boomerangs.py"	
@@ -0,0 +1,31 @@
+'''
+1. 아이디어 :
+- 각 점을 기준으로 다른 점들과의 거리를 계산하고, 같은 거리를 가진 점들의 개수를 세어 부메랑의 수를 계산.
+- 이거 원래 3중 for문 돌았는데 그러면 시간초과난다.
+2. 시간복잡도 :
+o(n^2)
+3. 자료구조/알고리즘 :
+'''
+
+from collections import defaultdict
+class Solution:
+    def numberOfBoomerangs(self, points: list[list[int]]) -> int:
+        n = len(points)
+        if n < 3:
+            return 0
+
+        ans = 0
+        for i in range(n):
+            dic = defaultdict(int)
+            for j in range(n):
+                x1,y1 = points[i]
+                x2,y2 = points[j]
+                dic[(x2-x1)** 2 + (y2-y1)**2] += 1
+            # print(dic)
+            for value in dic.values():
+                if value >= 2:
+                    ans += value * (value -1)
+                
+        
+        return ans
+                    
\ No newline at end of file