diff --git a/climbing-stairs/daehyun99.py b/climbing-stairs/daehyun99.py
new file mode 100644
index 0000000000..09681c6150
--- /dev/null
+++ b/climbing-stairs/daehyun99.py
@@ -0,0 +1,20 @@
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        one_count = n
+        two_count = 0
+        total_count = 0
+
+        while one_count >=0 and two_count >=0:
+            # 조합
+            total = one_count + two_count
+
+            count = 1
+            for i in range(two_count):
+                count *= total - i
+            for i in range(two_count, 0, -1):
+                count /= i
+            total_count += count
+
+            one_count -=2
+            two_count +=1
+        return int(total_count)
diff --git a/product-of-array-except-self/daehyun99.py b/product-of-array-except-self/daehyun99.py
new file mode 100644
index 0000000000..26e3fee3e2
--- /dev/null
+++ b/product-of-array-except-self/daehyun99.py
@@ -0,0 +1,18 @@
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        product = 1
+        zero_pos = set()
+
+        for i in range(len(nums)):
+            num = nums[i]
+            if num != 0:
+                product *= num
+            else:
+                zero_pos.add(i)
+        
+        if len(zero_pos) >= 2:
+            return [0 for num in nums]
+        elif len(zero_pos) == 1:
+            return [0 if i not in zero_pos else product for i in range(len(nums))]
+        else:
+            return [int(product / num) for num in nums]
diff --git a/valid-anagram/daehyun99.py b/valid-anagram/daehyun99.py
new file mode 100644
index 0000000000..bfcc871ed1
--- /dev/null
+++ b/valid-anagram/daehyun99.py
@@ -0,0 +1,16 @@
+from collections import defaultdict
+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        count = defaultdict(int)
+
+        if len(s) != len(t):
+            return False
+
+        for s_, t_ in zip(s, t):
+            count[s_] += 1
+            count[t_] -= 1
+        
+        for key, val in count.items():
+            if val != 0:
+                return False
+        return True