From f24eb511c36b55e2bab154b37b5309e9c05f61ae Mon Sep 17 00:00:00 2001
From: SEON MI KIM <dev.ddubbu@gmail.com>
Date: Tue, 13 Aug 2024 22:16:27 +0900
Subject: [PATCH] [Gold IV] Title: N-Queen, Time: 25660 ms, Memory: 34272 KB
 -BaekjoonHub

---
 .../N\357\274\215Queen.py"                    | 43 ++++++-------------
 .../README.md"                                |  4 +-
 2 files changed, 15 insertions(+), 32 deletions(-)

diff --git "a/\353\260\261\354\244\200/Gold/9663.\342\200\205N\357\274\215Queen/N\357\274\215Queen.py" "b/\353\260\261\354\244\200/Gold/9663.\342\200\205N\357\274\215Queen/N\357\274\215Queen.py"
index ba351e5..7386e8c 100644
--- "a/\353\260\261\354\244\200/Gold/9663.\342\200\205N\357\274\215Queen/N\357\274\215Queen.py"
+++ "b/\353\260\261\354\244\200/Gold/9663.\342\200\205N\357\274\215Queen/N\357\274\215Queen.py"
@@ -9,45 +9,26 @@
 y_pos_arr = [-1] * N
 
 
-정방향_cross = [True] * ((2 * N) - 1)  # i + j
-역방향_cross = [True] * ((2 * N) - 1)  # i - j + N - 1
-
-
-def check_is_정방향_cross(x_pos, y_pos):
-    return 정방향_cross[x_pos + y_pos]
-
-
-def check_is_역방향_cross(x_pos, y_pos):
-    return 역방향_cross[x_pos - y_pos + N - 1]
+used_cols = [True] * N
+정방향_cross = [True] * (N << 1)  # 2N-1
+역방향_cross = [True] * (N << 1)  # (최적화) 비트 연산자로 2배처리
 
 
 def set_queen(x_pos, y_pos):
+    y_pos_arr[x_pos] = y_pos
     정방향_cross[x_pos + y_pos] = False
     역방향_cross[x_pos - y_pos + N - 1] = False
-    y_pos_arr[x_pos] = y_pos
+    used_cols[y_pos] = False
 
 
 def reset_queen(x_pos, y_pos):
+    y_pos_arr[x_pos] = -1
     정방향_cross[x_pos + y_pos] = True
     역방향_cross[x_pos - y_pos + N - 1] = True
-    y_pos_arr[x_pos] = -1
-
-
-def check_valid_pos(x_pos, y_pos):
-    # 열 중복
-    if y_pos in y_pos_arr:
-        return False
-
-    # 대각선 중복
-    if check_is_정방향_cross(x_pos, y_pos) and check_is_역방향_cross(x_pos, y_pos):
-        return True
-
-    return False
-
+    used_cols[y_pos] = True
 
 cnt = 0
 
-
 def dfs(x_pos):
     # 주의) x_pos; depth 정의 필요! y_pos_arr 만으로 관리할 수 있다고 생각했음
 
@@ -58,10 +39,12 @@ def dfs(x_pos):
         return
 
     for y_pos in range(N):
-        if check_valid_pos(x_pos, y_pos):
-            set_queen(x_pos, y_pos)
-            dfs(x_pos + 1)
-            reset_queen(x_pos, y_pos)
+        if not (used_cols[y_pos] and 정방향_cross[x_pos + y_pos] and 역방향_cross[x_pos - y_pos + N - 1]):
+            continue
+            
+        set_queen(x_pos, y_pos)
+        dfs(x_pos + 1)
+        reset_queen(x_pos, y_pos)
 
 
 dfs(0)
diff --git "a/\353\260\261\354\244\200/Gold/9663.\342\200\205N\357\274\215Queen/README.md" "b/\353\260\261\354\244\200/Gold/9663.\342\200\205N\357\274\215Queen/README.md"
index 5bb24cf..91cbae2 100644
--- "a/\353\260\261\354\244\200/Gold/9663.\342\200\205N\357\274\215Queen/README.md"
+++ "b/\353\260\261\354\244\200/Gold/9663.\342\200\205N\357\274\215Queen/README.md"
@@ -4,7 +4,7 @@
 
 ### 성능 요약
 
-메모리: 120364 KB, 시간: 9184 ms
+메모리: 34272 KB, 시간: 25660 ms
 
 ### 분류
 
@@ -12,7 +12,7 @@
 
 ### 제출 일자
 
-2024년 8월 13일 21:34:09
+2024년 8월 13일 22:10:20
 
 ### 문제 설명