uva10618

#include<iostream>
#include<algorithm>
#include<math.h>
#include<string.h>
#include<stdio.h>
#include<string>
#include<vector>
#include<queue>
#include<map>
#include<sstream>
using namespace std;
const int maxn = 70+5;
const int UP = 0;
const int LEFT = 1;
const int RIGHT = 2;
const int DOWN = 3;

int d[maxn][4][4][3];
int action[maxn][4][4][3];
char seq[maxn], pos[256], footch[] = ".LR";

int energy(int a, int ta) {
	if (a == ta)return 3;
	if (a + ta == 3)return 7;
	return 5;
}

int energy(int i, int a, int b, int s, int f, int &ta, int &tb, int t) {//ta,tb是移动过后的，也就是i+1，f是上一次的集合
	ta = a; tb = b;
	if (f == 1)ta = t;
	else if (f == 2)tb = t;
	if (ta == tb)return -1;
	if (a == RIGHT && tb != b)return -1;
	if (b == LEFT && ta != a)return -1;
	if (ta == RIGHT && tb == LEFT)return -1;

	int e;
	if (f == 0)e = 0;
	else if (f != s)e = 1;
	else {
		if (f == 1)e = energy(a, ta);
		else e = energy(b , tb);
	}
	return e;
}

void update(int i, int a, int b, int s, int f,int t) {
	int ta, tb;
	int e = energy(i, a, b, s, f, ta,tb,t);
	if (e < 0)return;
	int cost = d[i + 1][ta][tb][f] + e;
	int &ans = d[i][a][b][s];
	if (cost < ans) {
		ans = cost;
		action[i][a][b][s] = f * 4 + t;
	}
}
int main() {
	pos['U'] = 0; pos['L'] = 1; pos['R'] = 2; pos['D'] = 3;
	while (scanf("%s", seq) == 1) {
		if (seq[0] == '#')break;
		int n = strlen(seq);
		memset(seq, 0, sizeof(seq));
		for (int i = n - 1; i >= 0; i--) {
			for (int a = 0; a < 4; a++) {
				for (int b = 0; b < 4; b++)if(a!=b) {
					for (int s = 0; s < 3; s++) {
						d[i][a][b][s] = 10 * n;
						if (seq[i] == '.') {
							update(i, a, b, s, 0, 0);//no move
							for (int t = 0; t < 4; t++) {
								update(i, a, b, s, 1, t);//move a
								update(i, a, b, s, 2, t);//move b
							}
						}
						else {
							update(i, a, b, s, 1, pos[seq[i]]);//move a
							update(i, a, b, s, 2, pos[seq[i]]);//move b
						}
					}
				}
			}
		}
		int a = LEFT, b = RIGHT, s = 0;
		for (int i = 0; i < n; i++) {
			int f = action[i][a][b][s] / 4;
			int t = action[i][a][b][s] % 4;
			cout << footch[f];
			s = f;
			if (f == 1)a = t;
			else if (f == 2)b = t;
		}
		cout << endl;
	}
	return 0;
}