Educational Codeforces Round 84 (Rated for Div. 2) C. Game with Chips

C. Game with Chips
time limit per test1 second
memory limit per test256 megabytes
inputstandard input
outputstandard output
Petya has a rectangular Board of size n×m. Initially, k chips are placed on the board, i-th chip is located in the cell at the intersection of sxi-th row and syi-th column.

In one action, Petya can move all the chips to the left, right, down or up by 1 cell.

If the chip was in the (x,y) cell, then after the operation:

left, its coordinates will be (x,y−1);
right, its coordinates will be (x,y+1);
down, its coordinates will be (x+1,y);
up, its coordinates will be (x−1,y).
If the chip is located by the wall of the board, and the action chosen by Petya moves it towards the wall, then the chip remains in its current position.

Note that several chips can be located in the same cell.

For each chip, Petya chose the position which it should visit. Note that it’s not necessary for a chip to end up in this position.

Since Petya does not have a lot of free time, he is ready to do no more than 2nm actions.

You have to find out what actions Petya should do so that each chip visits the position that Petya selected for it at least once. Or determine that it is not possible to do this in 2nm actions.

Input
The first line contains three integers n,m,k (1≤n,m,k≤200) — the number of rows and columns of the board and the number of chips, respectively.

The next k lines contains two integers each sxi,syi (1≤sxi≤n,1≤syi≤m) — the starting position of the i-th chip.

The next k lines contains two integers each fxi,fyi (1≤fxi≤n,1≤fyi≤m) — the position that the i-chip should visit at least once.

Output
In the first line print the number of operations so that each chip visits the position that Petya selected for it at least once.

In the second line output the sequence of operations. To indicate operations left, right, down, and up, use the characters L,R,D,U respectively.

If the required sequence does not exist, print -1 in the single line.

Examples
inputCopy
3 3 2
1 2
2 1
3 3
3 2
outputCopy
3
DRD
inputCopy
5 4 3
3 4
3 1
3 3
5 3
1 3
1 4
outputCopy
9
DDLUUUURR

题意:
给你 k 个点，告诉你它们的起点和终点，让你找一条路径，使每个点至少经过终点一次，路径长度不超过2nm
每一次移动是所有点一起移动。
思路：
观察到数据范围只有1—200，所以直接暴力就好了，让每个点都把整个图跑一遍（这样随便你起点终点在哪，都能保证至少走了一遍）。
像这样走

第二遍倒着走就好了，刚好 2nm步，走完后所有的点都把图跑了一遍。

#include
#include
#include
#include
#include
#include
#include
using namespace std;
typedef long long ll;
const int maxn=1e5+7;
int n,m,k;
int x,y;
int main(){
    cin>>n>>m>>k;
    for(int i=0;i<2*k;i++) scanf("%d%d",&x,&y);
    printf ("%d\n",2*n*m);
    for(int i=0;i<m;i++){
        if(i%2==1){
            for(int i=0;i<n-1;i++) printf ("U");
            printf ("R");
        }
        if(i%2==0){
            for(int i=0;i<n-1;i++) printf ("D");
            printf ("R");
        }
    }
    for(int i=0;i<m;i++){     //倒着走注意先向上还是向下
        if((i+m)%2==1){  
            for(int i=0;i<n-1;i++) printf ("U");
            printf ("L");
        }
        if((i+m)%2==0){
            for(int i=0;i<n-1;i++) printf ("D");
            printf ("L");
        }
    }


}