From dbde40d2f7870495b2902e1ee88ffa0cee4d6df0 Mon Sep 17 00:00:00 2001
From: Yerim Moon <myr9901@gmail.com>
Date: Fri, 13 Mar 2026 16:20:43 -0700
Subject: [PATCH 1/4] climing stairs solution

---
 climbing-stairs/yerim01.py | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 climbing-stairs/yerim01.py

diff --git a/climbing-stairs/yerim01.py b/climbing-stairs/yerim01.py
new file mode 100644
index 0000000000..5cee23f7ac
--- /dev/null
+++ b/climbing-stairs/yerim01.py
@@ -0,0 +1,34 @@
+# Goal: Given n steps, return the number of distinct ways you can climb to the top.
+# Constraints:
+# - You can climb either 1 or 2 steps at each time.
+# - 1 <= n <= 45
+# Approach:
+# f(n) = number of ways to reach step n.
+# The last move must be from step n-1 or step n-2.
+# Therefore, f(n) = f(n-1) + f(n-2).
+# Base case - f(1) = 1, f(2) = 2.
+# Use two variables prev1&prev2 to track the number of of f(n-1)&f(n-2).
+# Iterate a loop, staring from 3.
+# Store prev1 into temp.
+# Update prev1&prev2.
+# Return prev1.
+
+# Time complexity: O(n)
+# - We iterate once
+# Space complexity: O(1)
+# - Only using variables
+
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        if n <= 2:
+            return n
+        
+        prev1 = 2
+        prev2 = 1
+
+        for i in range(3, n+1):
+            temp = prev1
+            prev1 = prev2 + prev1
+            prev2 = temp
+        
+        return prev1
\ No newline at end of file

From 45b8cf2d0def0043f27642193590a4e8922ed97c Mon Sep 17 00:00:00 2001
From: Yerim Moon <myr9901@gmail.com>
Date: Fri, 13 Mar 2026 16:58:03 -0700
Subject: [PATCH 2/4] product of array except self solution

---
 product-of-array-except-self/yerim01.py | 30 +++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 product-of-array-except-self/yerim01.py

diff --git a/product-of-array-except-self/yerim01.py b/product-of-array-except-self/yerim01.py
new file mode 100644
index 0000000000..15b3fdee83
--- /dev/null
+++ b/product-of-array-except-self/yerim01.py
@@ -0,0 +1,30 @@
+# Goal: Return an array answer that product of all elements except nums[i].
+#
+# Approach:
+# Use prefix&suffix arrays to store cumulative products
+# - prefix: product of elements to the left of i
+# - suffix: product of elements to the right of i
+# Calculate the result[i] by multipying prefix[i] and suffix[i]
+#
+# Time Complexity: O(n)
+# - We Iterate the array to compute prefix, suffix and result.
+# Space Complexity: O(n)
+# - We use extra arrays for prefix&suffix.
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        n = len(nums)
+
+        prefix = [1] * n
+        suffix = [1] * n
+        result = [1] * n
+
+        for i in range(1, n):
+            prefix[i] = prefix[i-1] * nums[i-1]
+        
+        for i in range(n-2, -1, -1):
+            suffix[i] = suffix[i+1] * nums[i+1]
+        
+        for i in range(len(nums)):
+            result[i] = prefix[i] * suffix[i]
+        
+        return result
\ No newline at end of file

From dfca88d83cdd6a4bf3375483da86b8f51989caff Mon Sep 17 00:00:00 2001
From: Yerim Moon <myr9901@gmail.com>
Date: Fri, 13 Mar 2026 17:04:06 -0700
Subject: [PATCH 3/4] =?UTF-8?q?=EA=B0=9C=ED=96=89=EB=AC=B8=EC=9E=90=20?=
 =?UTF-8?q?=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 product-of-array-except-self/yerim01.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/product-of-array-except-self/yerim01.py b/product-of-array-except-self/yerim01.py
index 15b3fdee83..17f0ed4572 100644
--- a/product-of-array-except-self/yerim01.py
+++ b/product-of-array-except-self/yerim01.py
@@ -27,4 +27,4 @@ def productExceptSelf(self, nums: List[int]) -> List[int]:
         for i in range(len(nums)):
             result[i] = prefix[i] * suffix[i]
         
-        return result
\ No newline at end of file
+        return result

From c12a07f62d795a4b1296743b264be1c7814a7ea8 Mon Sep 17 00:00:00 2001
From: Yerim Moon <myr9901@gmail.com>
Date: Fri, 13 Mar 2026 17:11:32 -0700
Subject: [PATCH 4/4] =?UTF-8?q?=EA=B0=9C=ED=96=89=EB=AC=B8=EC=9E=90=20?=
 =?UTF-8?q?=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 climbing-stairs/yerim01.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/climbing-stairs/yerim01.py b/climbing-stairs/yerim01.py
index 5cee23f7ac..8030fa28e5 100644
--- a/climbing-stairs/yerim01.py
+++ b/climbing-stairs/yerim01.py
@@ -31,4 +31,4 @@ def climbStairs(self, n: int) -> int:
             prev1 = prev2 + prev1
             prev2 = temp
         
-        return prev1
\ No newline at end of file
+        return prev1