Robot Motion
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)
题目大意:看图+样例基本就懂了。
结题思路:模拟
Code:
1 #include<string> 2 #include<iostream> 3 #include<cstdio> 4 #include<cstring> 5 using namespace std; 6 int a,b,first,px,py,date1,date2; 7 struct Point 8 { 9 char dir; 10 int vis,step; 11 } P[1000]; 12 int move(int cnt) 13 { 14 int tmp=(py-1)*a+px; 15 if (P[tmp].dir==‘N‘) py--; 16 if (P[tmp].dir==‘E‘) px++; 17 if (P[tmp].dir==‘S‘) py++; 18 if (P[tmp].dir==‘W‘) px--; 19 if (px>=a+1||px<=0||py>=b+1||py<=0) 20 return 1; 21 tmp=(py-1)*a+px; 22 if (P[tmp].vis) 23 { 24 date1=P[tmp].step-1; 25 date2=cnt-date1-1; 26 return -1; 27 } 28 else P[tmp].vis=1,P[tmp].step=cnt; 29 return 0; 30 } 31 int main() 32 { 33 while (cin>>b>>a>>first) 34 { 35 int k=1; 36 if (!a&&!b&&!first) break; 37 for (int i=1; i<=b; i++) 38 for (int j=1; j<=a; j++) 39 { 40 cin>>P[k].dir; 41 P[k++].vis=0; 42 } 43 px=first,py=1; 44 P[first].step=1,P[first].vis=1; 45 int cnt=2,ok; 46 while (1) 47 { 48 ok=move(cnt); 49 if (ok) break; 50 cnt++; 51 } 52 if (ok==1) printf("%d step(s) to exit\n",cnt-1); 53 else printf("%d step(s) before a loop of %d step(s)\n",date1,date2); 54 } 55 return 0; 56 }
POJ1573——Robot Motion,布布扣,bubuko.com
原文:http://www.cnblogs.com/Enumz/p/3764602.html