搜索，最短路都可以
#include<stdio.h>
#include<string.h>
#include<queue>
#define inf 0x3fffffff
using namespace std;
int map[65][65];
int sx,sy,ex,ey;
int dis[10][10],link[10][10];
char str[8][3]={"D","R","U","L","RD","LU","LD","RU"};
int dir[8][2]={1,0,0,1,-1,0,0,-1,1,1,-1,-1,1,-1,-1,1};
struct node
{
int x,y,w;
friend bool operator < (node a, node b)
{
return a.w>b.w;
}
}cur,next;
int judge(int x,int y)
{
if(x>=1&&x<=8&&y>=1&&y<=8)
return 1;
return 0;
}
void bfs()
{
priority_queue<node> Q;
int x,y,i,w,j;
for(i=0;i<9;i++)
for(j=0;j<9;j++)
dis[i][j]=inf;
cur.x=sx;cur.y=sy;cur.w=0;
dis[sx][sy]=0;
Q.push(cur);
while(!Q.empty())
{
cur=Q.top();
Q.pop();
if(cur.x==ex&&cur.y==ey)return;
for(i=0;i<8;i++)
{
next.x=x=cur.x+dir[i][0];
next.y=y=cur.y+dir[i][1];
if(judge(x,y)==0)continue;
next.w=w=cur.w+1;
if(w<dis[x][y])
{
dis[x][y]=w;
Q.push(next);
link[x][y]=i;
}
}
}
}
void prinf(int x,int y)
{
if(x==sx&&y==sy)return ;
int i=link[x][y];
prinf(x-dir[i][0],y-dir[i][1]);
printf("%s\n",str[i]);
}
int main()
{
char s1[5],s2[5];
while(scanf("%s%s",s1,s2)!=-1)
{
sy=s1[0]-'a'+1;
sx=9-(s1[1]-'0');
ey=s2[0]-'a'+1;
ex=9-(s2[1]-'0');
bfs();
printf("%d\n",dis[ex][ey]);
prinf(ex,ey);
}
return 0;
}