Shortest path of the king

最新推荐文章于 2018-12-07 21:48:00 发布

转载最新推荐文章于 2018-12-07 21:48:00 发布 · 60 阅读

本文介绍了一个关于国际象棋中国王从一个位置移动到另一个位置的最短路径问题，并提供了一段C++代码实现。该算法考虑了所有可能的移动方向，并针对不同起始和结束位置给出了最优解。

The king is left alone on the chessboard. In spite of this loneliness, he doesn't lose heart, because he has business of national importance. For example, he has to pay an official visit to square t. As the king is not in habit of wasting his time, he wants to get from his current position s to square t in the least number of moves. Help him to do this.

$\text{[math]}$

In one move the king can get to the square that has a common side or a common vertex with the square the king is currently in (generally there are 8 different squares he can move to).

Input

The first line contains the chessboard coordinates of square s, the second line — of square t.

Chessboard coordinates consist of two characters, the first one is a lowercase Latin letter (from a to h), the second one is a digit from 1to 8.

Output

In the first line print n — minimum number of the king's moves. Then in n lines print the moves themselves. Each move is described with one of the 8: L, R, U, D, LU, LD, RU or RD.

L, R, U, D stand respectively for moves left, right, up and down (according to the picture), and 2-letter combinations stand for diagonal moves. If the answer is not unique, print any of them.

Examples

input

a8
h1

output

7
RD
RD
RD
RD
RD
RD
RD

#include<iostream>
#include<stdio.h>
#include<queue>
#include<cstring>
using namespace std;
struct Node
{
    char x;
    int y;
} s,e;
int main()
{
    scanf("%c%d\n%c%d",&s.x,&s.y,&e.x,&e.y);
    int startx=s.x-'a';
    int endx=e.x-'a';
    int dx=endx-startx;
    int dy=e.y-s.y;
    int ma=max(abs(dx),abs(dy));
    int mi=min(abs(dx),abs(dy));
    if(dx>=0&&dy>=0)
    {
        printf("%d\n",ma);
        for(int i=0;i<mi;i++) printf("RU\n");
        for(int i=mi;i<ma;i++)
            printf("%c\n",dx==ma?'R':'U');
    }
    else if(dx<0&&dy<0)
    {
        dx*=-1;
        dy*=-1;
        printf("%d\n",ma);
        for(int i=0;i<mi;i++)
            printf("LD\n");
        for(int i=mi;i<ma;i++)
            printf("%c\n",dx==ma?'L':'D');
    }
    else if(dx>=0&&dy<0)
    {
        dy*=-1;
        printf("%d\n",ma);
        for(int i=0;i<mi;i++)
            printf("RD\n");
        for(int i=mi;i<ma;i++)
            printf("%c\n",dx==ma?'R':'D');
    }
    else if(dx<0&&dy>=0)
    {
        dx*=-1;
        printf("%d\n",ma);
        for(int i=0;i<mi;i++)
            printf("LU\n");
        for(int i=mi;i<ma;i++)
            printf("%c\n",dx==ma?'L':'U');
    }
    return 0;
}