Robot Motion
| Time Limit: 1000MS | Memory Limit: 10000K | |
| Total Submissions: 9449 | Accepted: 4594 |
Description
A robot has been programmed to follow the instructions in its path. Instructions for the next direction the robot is to move are laid down in a grid. The possible instructions are
N north (up the page)
S south (down the page)
E east (to the right on the page)
W west (to the left on the page)
For example, suppose the robot starts on the north (top) side of Grid 1 and starts south (down). The path the robot follows is shown. The robot goes through 10 instructions in the grid before leaving the grid.
Compare what happens in Grid 2: the robot goes through 3 instructions only once, and then starts a loop through 8 instructions, and never exits.
You are to write a program that determines how long it takes a robot to get out of the grid or how the robot loops around.
Input
There will be one or more grids for robots to navigate. The data for each is in the following form. On the first line are three integers separated by blanks: the number of rows in the grid, the number of columns in the grid, and the number of the column in
which the robot enters from the north. The possible entry columns are numbered starting with one at the left. Then come the rows of the direction instructions. Each grid will have at least one and at most 10 rows and columns of instructions. The lines of instructions
contain only the characters N, S, E, or W with no blanks. The end of input is indicated by a row containing 0 0 0.
Output
For each grid in the input there is one line of output. Either the robot follows a certain number of instructions and exits the grid on any one the four sides or else the robot follows the instructions on a certain number of locations once, and then the instructions
on some number of locations repeatedly. The sample input below corresponds to the two grids above and illustrates the two forms of output. The word "step" is always immediately followed by "(s)" whether or not the number before it is 1.
Sample Input
3 6 5 NEESWE WWWESS SNWWWW 4 5 1 SESWE EESNW NWEEN EWSEN 0 0 0
Sample Output
10 step(s) to exit 3 step(s) before a loop of 8 step(s)
題目大意：
10 * 10的地圖，機器人移動規則是：按照上北，下南，左西，右東進行移動，直到到達出口。入口則是第一行某一列，列數爲輸入第三個數據。
#include <stdio.h>
#include <memory.h>
int mark[12][12];
char map[12][12];
int main()
{
int i,j,m,n,sta,x,y,row,col,count;
while(scanf("%d%d%d",&m,&n,&sta) && m && n && sta)
{
getchar();//注意此處吸收掉一個回車
count = 0;
memset(map,'O',sizeof(map));//map數組需要多加一圈'O'(大寫字母O)，以判斷出界情況.
memset(mark,0,sizeof(mark));//標記數組，用來記錄某一位置走過幾次
for(i=1; i<=m; i++)
{
for(j=1; j<=n; j++)
{
scanf("%c",&map[i][j]);
}
getchar();//注意換行出回車也需要吸收掉
}
x = 1;//起始行爲第一行
y = sta;//起始列爲輸入的sta
while(1)
{
mark[x][y] ++;//標記數組加一，必須再條件判斷之前加，否則起始位置沒有加。（表示被此處坑過，一直wa）
if(map[x][y] == 'N')
x --;
else if(map[x][y] == 'S')
x ++;
else if(map[x][y] == 'W')
y --;
else if(map[x][y] == 'E')
y ++;
else if(map[x][y] == 'O')//遇到出口，輸出，跳出
{
printf("%d step(s) to exit\n",count);
break;
}
count ++;//計數變量加一，經驗證，此處不可更換位置。
if(mark[x][y] == 2)//如果某處走過兩次，說明此處是環的起始位置
{
row = x;//記錄此處座標
col = y;
mark[x][y] = 1;//此處走過此處置爲1
x = 1;//從起點位置重新走
y = sta;
count = 0;//計數變量置0
while(1)
{
if(x == row && y == col && mark[x][y] == 1)//進入環的起點
{
printf("%d step(s) before a loop of ",count);//輸出入環之前走的步數
mark[x][y] ++;//標記此位置加一
count = 0;//count置0
}
if(x == row && y == col && mark[x][y] == 2 && count != 0)//再次到這個位置，即環的終點
{
printf("%d step(s)\n",count);//輸出環的長度
break;
}
//機器人的移動
if(map[x][y] == 'N')
x --;
else if(map[x][y] == 'S')
x ++;
else if(map[x][y] == 'W')
y --;
else if(map[x][y] == 'E')
y ++;
count ++;//每移動一次，計數變量加一
}
break;
}
}
}
return 0;
}