我完全陷入了本周结束的家庭作业。
由于一些愚蠢的原因，我的递归遍历在它到达我的迷宫（'E'）结束时没有停止，但继续前进。
以下是读者：
public class mainProg {
public static void main(String[] args) {
// The name of the file to open.
Scanner reader = new Scanner(System.in); // Reading from System.in
System.out.println("Enter the name of textfile to be read ( add .txt): ");
String fileName = reader.next();
char temp;
// This will reference one line at a time
String line = null;
int count = 1;
int heightCounter = 0;
try {
// FileReader reads text files in the default encoding.
FileReader fileReader =
new FileReader(fileName);
// Always wrap FileReader in BufferedReader.
BufferedReader bufferedReader =
new BufferedReader(fileReader);
int height = 0, width = 0, startx = 0, starty = 0, endx = 0, endy= 0;
char [][] maze = null;
while((line = bufferedReader.readLine()) != null) {
System.out.println(line);
switch (count) {
case (1):
height = Integer.parseInt(line.substring(0, line.indexOf(' ')));
width = Integer.parseInt((line.substring(line.indexOf(' ')+1)));
maze = new char [height][width];
break;
case (2):
temp = line.charAt(0);
starty = Character.getNumericValue(temp);
temp = line.charAt(2);
startx = Character.getNumericValue(temp);
break;
case (3):
endy = Integer.parseInt(line.substring(0, line.indexOf(' ')));
endx = Integer.parseInt((line.substring(line.indexOf(' ')+1)));
break;
default:
int counter = 0;
for (int iterator = 0; iterator < line.length(); iterator++){
if(line.charAt(iterator) != ' '){
maze[heightCounter][counter] = line.charAt(iterator);
counter++;
}
}
heightCounter++;
break;
}
count++;
}
maze[starty][startx] = 'S';
maze[endy][endx] = 'E';
mazeCreator ma = new mazeCreator(maze);
ma.start(starty, startx);
System.out.println(ma.result);
// Always close files.
bufferedReader.close();
System.out.println("Height: " + height + " Width: " + width);
System.out.println("Starty: " + starty + " Startx: " + startx);
System.out.println("Endy: " + endy + " Endx: " + endx);
System.out.println(ma.result);
}
catch(FileNotFoundException ex) {
System.out.println(
"Unable to open file '" +
fileName + "'");
}
catch(IOException ex) {
System.out.println(
"Error reading file '"
+ fileName + "'");
// Or we could just do this:
// ex.printStackTrace();
}
}
}
这是我的迷宫课程：
package com.todai.first.project.testMaze;
public class mazeCreator {
char [][] maze;
char PATH = 'x';
char VISITED = 'y';
String result = "";
int starty, startx;
public mazeCreator (char[][] maze){
this.maze = maze;
}
public void start (int starty, int startx) {
this.starty = starty;
this.startx = startx;
traverse(starty, startx);
}
private boolean isValid (int row, int col){
boolean valid = false;
if (row >= 0 && row < maze.length &&
col >= 0 && col < maze[row].length){
if (maze[row][col] == '0' || maze[row][col] == 'E' || maze[row][col] == PATH) {
valid = true;
}
}
return valid;
}
private boolean traverse (int row, int col) {
System.out.println("I'm here: \t" + row +","+ col + "\t :: " + maze[row][col]);
if (maze[row][col] == 'E'){
System.out.println("I WON!");
result = mazeToString();
return true;
}
else{
if (maze[row][col] == PATH){
maze[row][col] = VISITED;
} else {
maze[row][col] = PATH;
}
if (isValid(row+1, col)){
traverse(row+1, col);
}
if (isValid(row-1, col)){
traverse(row-1, col);
}
if (isValid(row, col+1)){
traverse(row, col+1);
}
if (isValid(row-1, col-1)){
traverse(row, col-1);
}
return false;
}
}
private String mazeToString(){
StringBuilder sb = new StringBuilder();
for (int i=0; i< this.maze.length; i++) {
for (int j=0; j < this.maze[i].length; j++) {
if (maze[i][j] == '1') {
maze[i][j] = '#';
}
sb.append(maze[i][j]);
}
sb.append("\n");
}
maze[starty][startx] = 'S';
return sb.toString();
}
}
这是我从控制台获得的输出（eclipse）：
Enter the name of textfile to be read ( add .txt):
small.txt
6 5
1 1
4 3
1 1 1 1 1
1 0 0 0 1
1 0 1 0 1
1 0 1 0 1
1 0 1 0 1
1 1 1 1 1
I'm here: 1,1 :: S
I'm here: 2,1 :: 0
I'm here: 3,1 :: 0
I'm here: 4,1 :: 0
I'm here: 3,1 :: x
I'm here: 4,1 :: x
I'm here: 2,1 :: x
I'm here: 1,1 :: x
I'm here: 1,2 :: 0
I'm here: 1,3 :: 0
I'm here: 2,3 :: 0
I'm here: 3,3 :: 0
I'm here: 4,3 :: E
I WON!
I'm here: 2,3 :: x
I'm here: 3,3 :: x
I'm here: 4,3 :: E
I WON!
I'm here: 1,3 :: x
I'm here: 2,2 :: #
I'm here: 1,2 :: x
I'm here: 2,2 :: x
#####
#Sxx#
#y#y#
#y#y#
#y#E#
#####
Height: 6 Width: 5
Starty: 1 Startx: 1
Endy: 4 Endx: 3
#####
#Sxx#
#y#y#
#y#y#
#y#E#
#####
你们可以清楚地看到它在找到“E”之后继续以递归方式调用自己。
任何线索？
答案 0 :(得分：5)
打印I WON!后，您返回true，但非递归调用会检查返回值，因此它们当然不会停止。更改调用以检查返回值：
if (isValid(row+1, col)) {
if (traverse(row+1, col))
return true;
}