A:12 人
B:0 人
C:16 人
D:6 人
E:12 人
E. 這是 TOI 會考的普通題嗎?
首殺:Fysty (47 mins)
A. TOI 也會出搜索題?
首殺:hank55663 (16 mins)
方法一:
方法二:
C. TOI 也會出 IMO 題?
首殺:PixelCat (44 mins)
D. TOI 也會出構造題?
首殺:8e7 (81 mins)
只要暴力枚舉遞迴枚舉所有可能情況可以,有辦法計算出在 \(\max(N,M) \le 8\) 的情況下,滿足上頁兩個觀察的不同黑格塗色方式並不多。
引理:假設 \(i < j < k\) 且 row \(i,k\) 都至少有一個黑格,定義 \(row\_ma_i\) 為第 \(i\) row 的黑格最大的 column 座標
那麼 \(row\_ma_j \ge \min(row\_ma_i, row\_ma_k)\)
根據此引理可以 \(O(n)\) 找出每個 row 的最大 coumn 座標至少有多大,最小的 column 座標至少有多小也能用類似方法求出
#
是一定要有黑格的位置11 13
#............ #............
..#.......... .##..........
.#........... .##..........
............. .............
.....#....... ...###.......
...#..#...... ...####......
.....#....... .....##......
............. .............
............. .............
..........#.. .........##..
.........#.#. .........###.
X
展示一種可能的連接所有連通塊的方式11 13
#............ #............ #............
..#.......... .##.......... X##..........
.#........... .##.......... .##..........
............. ............. ..XX.........
.....#....... ...###....... ...###.......
...#..#...... ...####...... ...####......
.....#....... .....##...... .....##XXX...
............. ............. .........X...
............. ............. .........X...
..........#.. .........##.. .........##..
.........#.#. .........###. .........###.
B. TOI 也會出字串題?
首殺:可惜此題沒人 AC :(
~~賽後 alvingogo 把賽中的 code 做常數優化後就 AC 了(但時限是標程 3 倍,應該不算卡常唷) ~~
此題在考驗大家用正確的順序 DP
要搞清楚一件事:
a
,\(s2=\)aa
,\(c=\)b
or
or
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