#AT2313. E - Last Rook
E - Last Rook
当前没有测试数据。
E - Last Rook
Score : $500$ points
Problem Statement
This is an interactive task (where your program interacts with the judge's program via input and output).
We have an $N$-by-$N$ chessboard and $N$ rooks. Below, the square at the $i$-th row from the top and $j$-th column from the left is denoted by $(i, j)$.
Consider placing the rooks on squares of the chessboard. Here, you have to place the rooks so that all of the following conditions are satisfied.
- No row contains two or more rooks.
- No column contains two or more rooks.
Now, $N-1$ rooks are placed on the chessboard so that all of the above conditions are satisfied. You will choose a square that is not occupied by a rook and place a rook on that square. (It can be proved that there is at least one square on which a rook can be placed under the conditions.)
However, you cannot directly see which squares of the chessboard are occupied by a rook.
Instead, you may ask at most $20$ questions to the judge in the following manner.
- You choose integers $A$, $B$, $C$, and $D$ such that $1 \leq A \leq B \leq N, 1 \leq C \leq D \leq N$, and ask the number of rooks in the rectangular region formed by the squares $(i, j)$ such that $A \leq i \leq B, C \leq j \leq D$.
Find a square to place a rook.
Constraints
- $2 \leq N \leq 10^3$
- $N$ is an integer.
Input and Output
This is an interactive task (where your program interacts with the judge's program via input and output).
First, receive the size of the chessboard, $N$, from Standard Input.
Next, repeat asking a question until you find a square to place a rook.
A question should be printed to Standard Output in the following format:
The response will be given from Standard Input in the following format:
``` $T$ ```Here, $T$ is the response to the question, or -1
if the question is invalid or more than $20$ questions have been asked.
When the judge returns -1
, the submission is already regarded as incorrect. In this case, terminate the program immediately.
When you find a square to place a rook, let $(X, Y)$ be that square and print an answer in the following format. Then, terminate the program immediately.
``` $!$ $X$ $Y$ ```If there are multiple appropriate answers, any of them will be accepted.