9850: ABC303 —— C - Dash
Description
Takahashi will make $N$ moves. The $i$-th move is as follows.
1. Let $(x,y)$ be his current coordinates. He consumes a health of $1$ to move to the following point, depending on $S_i$, the $i$-th character of $S$:
- $(x+1,y)$ if $S_i$ is `R`;
- $(x-1,y)$ if $S_i$ is `L`;
- $(x,y+1)$ if $S_i$ is `U`;
- $(x,y-1)$ if $S_i$ is `D`.
2. If Takahashi's health has become negative, he collapses and stops moving. Otherwise, if an item is placed at the point he has moved to, and his health is strictly less than $K$, then he consumes the item there to make his health $K$.
Determine if Takahashi can complete the $N$ moves without being stunned.
Input
```
$N$ $M$ $H$ $K$
$S$
$x_1$ $y_1$
$\vdots$
$x_M$ $y_M$
```
Output
Constraints
- $S$ is a string of length $N$ consisting of `R`, `L`, `U`, and `D`.
- $|x_i|,|y_i| \leq 2\times 10^5$
- $(x_i, y_i)$ are pairwise distinct.
- All values in the input are integers, except for $S$.
Sample 1 Input
4 2 3 1
RUDL
-1 -1
1 0
Sample 1 Output
Yes
Initially, Takahashi's health is 3. We describe the moves below.
-
1-st move: Si is R, so he moves to point (1,0). His health reduces to 2. Although an item is placed at point (1,0), he do not consume it because his health is no less than K=1.
-
2-nd move: Si is U, so he moves to point (1,1). His health reduces to 1.
-
3-rd move: Si is D, so he moves to point (1,0). His health reduces to 0. An item is placed at point (1,0), and his health is less than K=1, so he consumes the item to make his health 1.
-
4-th move: Si is L, so he moves to point (0,0). His health reduces to 0.
Thus, he can make the 4 moves without collapsing, so Yes should be printed. Note that the health may reach 0.
Sample 2 Input
5 2 1 5
LDRLD
0 0
-1 -1
Sample 2 Output
No
Initially, Takahashi's health is 1. We describe the moves below.
-
1-st move: Si is L, so he moves to point (−1,0). His health reduces to 0.
-
2-nd move: Si is D, so he moves to point (−1,−1). His health reduces to −1. Now that the health is −1, he collapses and stops moving.
Thus, he will be stunned, so No should be printed.
Note that although there is an item at his initial point (0,0), he does not consume it before the 1-st move, because items are only consumed after a move.