题目描述
Problem Statement
A robot is at the origin of a coordinate plane where the positive x-axis points to the right and the positive y-axis points upwards. Initially, the robot is facing the positive x-direction.
You will perform the following operation for $i=1,\ldots,N$ in this order.
- Rotate the robot 90 degrees clockwise or counterclockwise. Then, the robot moves forward A_i units in the direction it is facing.
Can the direction of rotation be chosen so that the robot will be at the coordinates (X,Y) after the N operations?
If it is possible, determine which direction, clockwise or counterclockwise, should be chosen for each operation.
Input
The input is given from Standard Input in the following format:
N X Y
$A_1 \ldots A_N$
Output
If the robot cannot be at the coordinates (X,Y) after the N operations, print No.
If the robot can be at the coordinates (X,Y) after the N operations, the first line should contain Yes, and the second line should contain a string S of length N that satisfies the following condition.
Condition: S consists of L and R, and the following choices can put the robot at the coordinates (X,Y) after the N operations: in the i-th operation, rotate the robot counterclockwise if the i-th character of S is L, and rotate it clockwise if it is R.
If there are multiple solutions, you may print any of them.
Constraints
- $1 \leq N \leq 80$
- $1 \leq A_i \leq 10^7$
- -$10^9\leq X,Y \leq 10^9$
- All input values are integers.
Sample Input 1
3 -2 4
3 2 1
Sample Output 1
Yes
LLR
Initially, the robot is at (0,0) and facing the positive x-direction. The following choices can put the robot at the coordinates (X,Y) after the N operations.
- First operation: Rotate the robot 90 degrees counterclockwise to face the positive y-direction. The robot moves forward A_1=3 units in the direction it is facing, and moves to (0,3).
- Second operation: Rotate the robot 90 degrees counterclockwise to face the negative x-direction. The robot moves forward A_2=2 units in the direction it is facing, and moves to (-2,3).
- Third operation: Rotate the robot 90 degrees clockwise to face the positive y-direction. The robot moves forward A_3=1 unit in the direction it is facing, and moves to (-2,4).
Sample Input 2
1 0 0
1
Sample Output 2
No
Sample Input 3
4 0 0
1 1 1 1
Sample Output 3
Yes
LRRR
Outputs such as LLLL and RRRR are also accepted.
Sample Input 4
14 2543269 -1705099
3 14 159 2653 58979 323846 2643383 2795028 841971 69399 37510 58 20 9
Sample Output 4
Yes
LLLLLLLLLRLRRR
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分