From 7881b80cd943b11ea53eb02868fc767f716fcad8 Mon Sep 17 00:00:00 2001
From: obzva <dngyng1000@gmail.com>
Date: Sat, 21 Sep 2024 00:30:06 +0900
Subject: [PATCH 1/2] Fix: Spiral Matrix

---
 spiral-matrix/flynn.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/spiral-matrix/flynn.cpp b/spiral-matrix/flynn.cpp
index 5f506ddea..b4bba80d5 100644
--- a/spiral-matrix/flynn.cpp
+++ b/spiral-matrix/flynn.cpp
@@ -8,7 +8,7 @@
  * - N:               열의 개수
  * 
  * - Time complexity: O(MN)
- * - Space complexity: O(1)
+ * - Space complexity: O(MN)
  */
 
 class Solution {

From d14eb06d8c8eb1bc96c5879a6260e8690c7a64df Mon Sep 17 00:00:00 2001
From: obzva <dngyng1000@gmail.com>
Date: Sat, 21 Sep 2024 00:44:32 +0900
Subject: [PATCH 2/2] Refactor: Spiral Matrix

---
 spiral-matrix/flynn.cpp | 67 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/spiral-matrix/flynn.cpp b/spiral-matrix/flynn.cpp
index b4bba80d5..cd9765431 100644
--- a/spiral-matrix/flynn.cpp
+++ b/spiral-matrix/flynn.cpp
@@ -56,3 +56,70 @@ class Solution {
         return res;
     }
 };
+
+/**
+ * 풀이
+ * - 위와 동일하지만, 방문 여부를 기록하기 위해 m * n 크기의 정수형 2차원 배열 대신
+ *   m 크기의 16비트 정수 배열을 사용합니다
+ * - 더 이상 입력 배열을 변형하지 않습니다
+ * - 공간복잡도가 개선되고 실제 공간 사용량도 줄어듭니다
+ * 
+ * Big O
+ * - M: 주어진 matrix의 행의 개수
+ * - N:               열의 개수
+ * 
+ * - Time complexity: O(MN)
+ * - Space complexity: O(M)
+ */
+
+class Solution {
+public:
+    pair<int, int> rotate(pair<int, int> dir) {
+        return {dir.second, -dir.first};
+    }  
+
+    pair<int, int> get_next(pair<int, int> curr, pair<int, int> dir) {
+        return {curr.first + dir.first, curr.second + dir.second};
+    }  
+
+    void mark_visited(vector<uint16_t>& visit, pair<int, int> curr) {
+        visit[curr.first] |= 1 << curr.second;
+    }
+
+    bool is_visited(vector<uint16_t> const visit, pair<int, int> curr) {
+        return visit[curr.first] & 1 << curr.second;
+    }
+
+    vector<int> spiralOrder(vector<vector<int>>& matrix) {
+        int m = matrix.size();
+        int n = matrix[0].size();
+        int cnt = m * n;
+
+        pair<int, int> curr = {0, 0};
+        pair<int, int> curr_dir = {0, 1};
+
+        vector<uint16_t> visit(m, 0);
+
+        vector<int> res;
+
+        while (cnt) {
+            res.push_back(matrix[curr.first][curr.second]);
+
+            mark_visited(visit, curr);
+            --cnt;
+            
+            pair<int, int> next = get_next(curr, curr_dir);
+
+            if (0 > next.first || next.first >= m
+                || 0 > next.second || next.second >= n
+                || is_visited(visit, next)) {
+                curr_dir = rotate(curr_dir);
+                curr = get_next(curr, curr_dir);
+            } else {
+                curr = next;
+            }
+        }
+
+        return res;
+    }
+};