#AT2344. D - LRUD Instructions
D - LRUD Instructions
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D - LRUD Instructions
Score : $400$ points
Problem Statement
There is a grid with $H$ horizontal rows and $W$ vertical columns. $(i, j)$ denotes the square at the $i$-th row from the top and $j$-th column from the left.
$N$ squares, $(r_1, c_1), (r_2, c_2), \ldots, (r_N, c_N)$, have walls.
Takahashi is initially at square $(r_\mathrm{s}, c_\mathrm{s})$.
$Q$ instructions are given to Takahashi.
For $i = 1, 2, \ldots, Q$, the $i$-th instruction is represented by a pair of a character $d_i$ and a positive integer $l_i$. $d_i$ is one of L
, R
, U
, and D
, representing the directions of left, right, up, and down, respectively.
Given the $i$-th direction, Takahashi repeats the following action $l_i$ times:
If a square without a wall is adjacent to the current square in the direction represented by $d_i$, move to that square; otherwise, do nothing.
For $i = 1, 2, \ldots, Q$, print the square where Takahashi will be after he follows the first $i$ instructions.
Constraints
- $2 \leq H, W \leq 10^9$
- $1 \leq r_\mathrm{s} \leq H$
- $1 \leq c_\mathrm{s} \leq W$
- $0 \leq N \leq 2 \times 10^5$
- $1 \leq r_i \leq H$
- $1 \leq c_i \leq W$
- $i \neq j \Rightarrow (r_i, c_i) \neq (r_j, c_j)$
- $(r_\mathrm{s}, c_\mathrm{s}) \neq (r_i, c_i)$ for all $i = 1, 2, \ldots, N$.
- $1 \leq Q \leq 2 \times 10^5$
- $d_i$ is one of the characters
L
,R
,U
, andD
. - $1 \leq l_i \leq 10^9$
- All values in the input other than $d_i$ are integers.
Input
The input is given from Standard Input in the following format:
Output
Print $Q$ lines. For $i = 1, 2, \ldots, Q$, the $i$-th line should contain the square $(R_i, C_i)$ where Takahashi will be after he follows the first $i$ instructions, in the following format:
``` $R_1$ $C_1$ $R_2$ $C_2$ $\vdots$ $R_Q$ $C_Q$ ```5 5 4 4
3
5 3
2 2
1 4
4
L 2
U 3
L 2
R 4
4 2
3 2
3 1
3 5
The given grid and the initial position of Takahashi are as follows, where #
denotes a square with a wall, T
a square where Takahashi is, and .
the other squares:
Given the $1$-st instruction, Takahashi moves $2$ squares to the left, ending up in square $(4, 2)$ as follows:
``` ...#. .#... ..... .T... ..#.. ```Given the $2$-nd instruction, Takahashi first moves $1$ square upward, then he "does nothing" twice because the adjacent square in his direction has a wall. As a result, he ends up in square $(3, 2)$ as follows:
``` ...#. .#... .T... ..... ..#.. ```Given the $3$-rd instruction, Takahashi first moves $1$ square to the left, then he "does nothing" once because there is no square in his direction. As a result, he ends up in square $(3, 1)$ as follows:
``` ...#. .#... T.... ..... ..#.. ```Given the $4$-th instruction, Takahashi moves $4$ squares to the right, ending up in square $(3, 5)$ as follows:
``` ...#. .#... ....T ..... ..#.. ```6 6 6 3
7
3 1
4 3
2 6
3 4
5 5
1 1
3 2
10
D 3
U 3
L 2
D 2
U 3
D 3
U 3
R 3
L 3
D 1
6 3
5 3
5 1
6 1
4 1
6 1
4 1
4 2
4 1
5 1