From 43cb051c3d8c9f5699e5b794761fee709ce2fa2b Mon Sep 17 00:00:00 2001
From: jonghun <jonghuncu@gmail.com>
Date: Thu, 19 Dec 2024 00:34:08 +0900
Subject: [PATCH 1/2] add week 3 solution

---
 3sum/rivkode.py            |  8 ++++++++
 climbing-stairs/rivkode.py | 20 ++++++++++++++++++++
 valid-anagram/rivkode.py   | 26 ++++++++++++++++++++++++++
 3 files changed, 54 insertions(+)
 create mode 100644 3sum/rivkode.py
 create mode 100644 climbing-stairs/rivkode.py
 create mode 100644 valid-anagram/rivkode.py

diff --git a/3sum/rivkode.py b/3sum/rivkode.py
new file mode 100644
index 000000000..c93384bf9
--- /dev/null
+++ b/3sum/rivkode.py
@@ -0,0 +1,8 @@
+from typing import List
+
+# use hashtable
+
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        result = []
+        return result
diff --git a/climbing-stairs/rivkode.py b/climbing-stairs/rivkode.py
new file mode 100644
index 000000000..9e030f10b
--- /dev/null
+++ b/climbing-stairs/rivkode.py
@@ -0,0 +1,20 @@
+# Time Complexity O(n)
+# - traversing for loop takes O(n)
+# Space Complexity O(n)
+# - appending for loop it takes O(n)
+
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        stage = [1, 2, 3]
+
+        for i in range(3, 45):
+            value = stage[i - 1] + stage[i - 2]
+            stage.append(value)
+
+        return stage[n - 1]
+
+if __name__ == "__main__":
+    solution = Solution()
+    result = solution.climbStairs(5)
+    print(result)
+
diff --git a/valid-anagram/rivkode.py b/valid-anagram/rivkode.py
new file mode 100644
index 000000000..2e44f029a
--- /dev/null
+++ b/valid-anagram/rivkode.py
@@ -0,0 +1,26 @@
+from typing import List
+
+# Time Complexity O(n log n)
+# - when sorting by sorted function(TimSort) for each string it takes O(nlogn)
+# - traversing for loop takes O(n)
+# Space Complexity O(n)
+# - when sorting takes O(n)
+
+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        s_sorted = sorted(s)
+        t_sorted = sorted(t)
+
+        for i in range(len(s_sorted)):
+            if s_sorted[i] != t_sorted[i]:
+                return False
+        return True
+
+if __name__ == "__main__":
+    solution = Solution()
+
+    s = "nagaram"
+    t = "anagram"
+
+    result = solution.isAnagram(s, t)
+    print(result)

From f88e7acf227c26e45b044c331dfbc2c2943c3e41 Mon Sep 17 00:00:00 2001
From: jonghun <jonghuncu@gmail.com>
Date: Sat, 21 Dec 2024 19:10:02 +0900
Subject: [PATCH 2/2] add week 3 solution

---
 3sum/rivkode.py | 67 +++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 62 insertions(+), 5 deletions(-)

diff --git a/3sum/rivkode.py b/3sum/rivkode.py
index c93384bf9..063ee7d5d 100644
--- a/3sum/rivkode.py
+++ b/3sum/rivkode.py
@@ -1,8 +1,65 @@
-from typing import List
+from typing import List, Tuple, Set
+
+# threeSum3()
+# Time Complexity O(n ^ 2)
+# - when sorting by sorted function(TimSort) for each string it takes O(nlogn)
+# - traversing for loop takes O(n) and check left and right in the while loop at the same time.
+# Space Complexity O(n)
+# - when sorting takes O(1)
 
-# use hashtable
 
 class Solution:
-    def threeSum(self, nums: List[int]) -> List[List[int]]:
-        result = []
-        return result
+    def threeSum(self, nums: List[int]) -> list[tuple[int, ...]]:
+
+        triplets = set()
+        for i in range(len(nums) - 2):
+            for j in range(i + 1, len(nums)):
+                for k in range(j + 1, len(nums)):
+                    if nums[i] + nums[j] + nums[k] == 0:
+                        triplet = [nums[i], nums[j], nums[k]]
+                        triplets.add(tuple(sorted(triplet)))
+
+        return list(triplets)
+
+    def threeSum2(self, nums: List[int]) -> list[tuple[int, ...]]:
+        triplets = set()
+
+        for i in range(len(nums)):
+            seen = set()
+            for j in range(i + 1, len(nums)):
+                res = -(nums[i] + nums[j])
+                if res in seen:
+                    triplet = [nums[i], nums[j], res]
+                    triplets.add(tuple(sorted(triplet)))
+                seen.add(nums[j])
+
+        return list(triplets)
+
+    def threeSum3(self, nums: List[int]) -> list(tuple[int, ...]):
+        triplets = set()
+        nums.sort()
+
+        for i in range(len(nums) - 2):
+            l = i + 1
+            r = len(nums) - 1
+
+            while l < r:
+                res = nums[l] + nums[r] + nums[i]
+                if res > 0:
+                    r -= 1
+                elif res < 0:
+                    l += 1
+                elif res == 0:
+                    triple = (nums[l], nums[r], nums[i])
+                    triplets.add(triple)
+                    l, r = l + 1, r - 1
+                else:
+                    raise Exception
+        return list(triplets)
+
+if __name__ == "__main__":
+    nums = [-1,0,1,2,-1,-4]
+
+
+    solution = Solution()
+    solution.threeSum3(nums)