使用 DFS 向我的主要问题传递参数 - Java
Issue passing argument to my main using DFS - Java
我试图在遍历我的 DFS 堆栈时尽可能快地获取此代码 运行ning 当前输入文件如下所示：
0 2
2 1
1 4
4 5
5 6
10 8
8 9
9 6
7 6
3 4
0 1
3 9
0 4
我的 Maze class 会将数字联系在一起并为我创建一个图表。创建图表后，我的 DFS class 运行 通过遍历为 .txt 文件提供一个或所有解决方案 submitted.I 最近改变了我的 Maze class 至于它 运行 更有效但是我被抛出错误并且数据正在解析到我的 DFS 以输出。我的Mazeclass如下：
import java.io.*;
import java.util.*;
public class Maze {
private final Map<Integer, Set<Integer>> adjList = new HashMap<>();
/**
* The main constructor that takes a String for reading maze file.
*
* @param file
*/
public Maze(File file) throws FileNotFoundException {
try (Scanner scan = new Scanner(file)) {
while (scan.hasNextInt()) {
int node1 = scan.nextInt();
int node2 = scan.nextInt();
this.connect(node1, node2);
this.connect(node2, node1);
}
}
}
/**
* Makes a unidirectional connection from node1 to node2.
*/
private void connect(int node1, int node2) {
if (!this.adjList.containsKey(node1)) {
this.adjList.put(node1, new HashSet<Integer>());
}
this.adjList.get(node1).add(node2);
}
/**
* Returns a human-readable description of the adjacency lists.
*/
public String toString() {
StringBuilder s = new StringBuilder();
for (Map.Entry<Integer, Set<Integer>> adj : this.adjList.entrySet()) {
int from = adj.getKey();
Set<Integer> to = adj.getValue();
s.append(from).append(" connected to ").append(to).append('\n');
}
return s.toString();
}
/**
* Returns the set of nodes connected to a particular node.
*
* @param node - the node whose neighbors should be fetched
*/
public Iterable<Integer> getadjList(int node) {
return Collections.unmodifiableSet(adjList.get(node));
}
/**
* Demonstration of file reading.
*/
public static void main(String[] args) throws FileNotFoundException {
System.err.print("Enter File: ");
Scanner scanFile = new Scanner(System.in);
String file = scanFile.nextLine();
Maze m = new Maze(new File(file));
System.out.println(m);
}
}
我的 DFS 看起来也是这样。
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.Stack;
public class DFS {
//starting node, the route to the next node, has node been visited
private int startNode;
private int[] route;
private boolean[] visited;
// 2 main arguments - Maze File & user input
public DFS(Maze maze, int inputInt) {
int startNode = 0;
int goalNode = 1;
route = new int[maze.node];
visited = new boolean[maze.node];
//Takes user's input and runs desired function
if(inputInt == 1){
findOne(maze, startNode, goalNode);
}
else if (inputInt == 2){
findAll(maze, startNode, goalNode);
}
else {
System.out.println("input invalid. No Solution Returned");
}
}
//Put path to goal in the stack
public Stack<Integer> route(int toGoalNode) {
if (!visited[toGoalNode]) {
return null;
}
Stack<Integer> pathStack = new Stack<Integer>();
for (int routeGoalNode = toGoalNode; routeGoalNode != startNode; routeGoalNode = route[routeGoalNode]) {
pathStack.push(routeGoalNode);
}
pathStack.push(startNode);
reverseStack(pathStack);
return pathStack;
}
//Reverse the stack
public void reverseStack(Stack<Integer> stackToBeReverse) {
if (stackToBeReverse.isEmpty()) {
return;
}
int bottom = popBottomStack(stackToBeReverse);
reverseStack(stackToBeReverse);
stackToBeReverse.push(bottom);
}
//Pop the bottom of the stack
private int popBottomStack(Stack<Integer> stackToBeReverse) {
int popTopStack = stackToBeReverse.pop();
if (stackToBeReverse.isEmpty()) {
return popTopStack;
} else {
int bottomStack = popBottomStack(stackToBeReverse);
stackToBeReverse.push(popTopStack);
return bottomStack;
}
}
//performs DFS and unsets visited to give the result of all paths
private void findAll(Maze maze, int node, int goal) {
visited[node] = true;
if(node == goal) {
printPath(goal);
} else {
for (int con : maze.getadjList(node)) {
if (!visited[con]) {
route[con] = node;
findAll(maze, con, goal);
}
}
}
visited[node] = false;
}
//performs DFS and maintains visited marker giving only one path
private void findOne(Maze maze, int node, int goal) {
visited[node] = true;
for (int con : maze.getadjList(node)) {
if (!visited[con]) {
route[con] = node;
findOne(maze, con, goal);
}
}
}
//Traverse the connections to the goal and print the path taken
public void printPath( int toGoal) {
int goalNode = 1;
if (visited[toGoal]) {
System.out.println("Completed Path: ");
for (int t : route(toGoal)) {
if (t == toGoal) {
System.out.print(t);
} else {
System.out.print(t + " -> ");
}
}
System.out.println();
}
}
public static void main(String[] args) throws FileNotFoundException {
Scanner scanFile = new Scanner(System.in);
int goalNode = 1;
System.out.print("Enter maze file: ");
String file = scanFile.nextLine();
Maze maze = new Maze(new File(file));
Scanner scanInt = new Scanner(System.in);
System.out.print("Enter desired feedback (1 = one soultion, 2 = all): ");
int inputInt = scanInt.nextInt();
// maze.toString();
System.out.println(maze);
DFS dfs = new DFS(maze, inputInt);
dfs.printPath(goalNode);
}
}
我已经查看了一段时间，无法弄清楚为什么要解析和使用数据。我在这里和那里改变了一些东西，但抛出了更多的错误。他们特别说
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
at DFS.findOne(DFS.java:90)
at DFS.<init>(DFS.java:22)
at DFS.main(DFS.java:127)
参考代码行：
visited[node] = true;
findOne(maze, startNode, goalNode);
DFS dfs = new DFS(maze, inputInt);
现在我基本上相信没有通过任何论点，如果有人能指出问题并帮助我解决问题，将不胜感激。再次感谢
编辑:: Maze class
的旧版本
import java.io.*;
import java.util.*;
public class Maze {
static Set<Integer> Nodes = new HashSet<Integer>();
List<Integer>[] conList;
int node; //declaring value for my nodes.
int con; // declaring a connection
//Constructor takes an int parameter to read through the list of corresponding nodes
Maze(int node) {
this.node = node;
this.con = 0;
conList = (List<Integer>[]) new List[node];
for (int index = 0; index < node; index++) {
conList[index] = new LinkedList<Integer>();
}
}
//Constructor that takes a String of the maze file
public Maze(String mazeFile) {
this(nodeSize(mazeFile));
Scanner scan;
try {
//Creates a scanner for reading the file and loops through linking the nodes to their connections.
scan = new Scanner(new File(mazeFile));
while (scan.hasNextInt()) {
int firstNode = scan.nextInt();
int secondNode = scan.nextInt();
addCon(firstNode, secondNode);
}
} catch (FileNotFoundException ex) {
System.out.println("File Not Found.");
}
}
/*Takes String parameter which is the name of the maze file.
* Method designed to return the the size of the set of nodes
*/
public static int nodeSize(String mazeFile) {
Scanner scanNodeSize;
try {
scanNodeSize = new Scanner(new File(mazeFile));
//while scan has more int's left repeat.
while (scanNodeSize.hasNextInt()) {
int firstNode = scanNodeSize.nextInt();
int secondNode = scanNodeSize.nextInt();
Nodes.add(firstNode);
Nodes.add(secondNode);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return Nodes.size();
}
//Method designed to connect the first and second nodes
private void addCon(int firstNode, int secondNode) {
con++;
conList[firstNode].add(secondNode);
conList[secondNode].add(firstNode);
}
//outputs the nodes and their connection's (#remove later?)
public void print() {
for (int n = 0; n < node; n++) {
System.out.print(n + " connected to ");
for (int w : conList[n]) {
System.out.print(w + " ");
}
System.out.println();
}
}
//method returns a list, enabling nodes to be easily accessible.
public Iterable<Integer> getconList(int nodes) {
return conList[nodes];
}
}
您在 0 处遇到索引越界异常。这会让您认为数组未正确初始化。您使用 maze.node 初始化 visited[] 数组，但是在您的代码中我们看不到这个节点变量所在的位置。如果你想让它 运行 可用，你需要给 maze.node 一个合适的值。
*编辑 - 我上面的答案不再适用，因为我们有你以前的迷宫 class 这解释了为什么代码不会 运行.
当前状态下的代码有很多问题，所以我会尝试在这里给你一些指导：
您创建迷宫的新方法是从文件中读取并连接 2 个点并将它们存储在地图中。这样做的问题是您不能只获取下一个元素，因为您必须拥有获取元素的密钥。要解决此问题，您应该使用不同的数据结构。
public DFS(Maze maze, int inputInt) {
int startNode = 0;
int goalNode = 1;
route = new int[maze.node]; //!!! maze.node isn't a thing anymore
visited = new boolean[maze.node]; //!!! maze.node isn't a thing anymore
您可以看到您正在尝试访问 maze.node，它曾经是 Maze 的一个变量。它不再是。您需要找到一种从 Maze 获取节点的新方法。为此，您需要以不同的方式从数据结构中获取节点：
public DFS(Maze maze, int inputInt) {
int startNode = 0;
int goalNode = 1;
route = new int[maze.adjList.getNode()];
visited = new boolean[maze.adjList.getNode()];
对于邻接表的不同数据结构，您有很多选择，但诸如此类：
http://theoryofprogramming.com/adjacency-list-in-java/
会给你一个不错的起点。
我试图在遍历我的 DFS 堆栈时尽可能快地获取此代码 运行ning 当前输入文件如下所示：
0 2 2 1 1 4 4 5 5 6 10 8 8 9 9 6 7 6 3 4 0 1 3 9 0 4
我的 Maze class 会将数字联系在一起并为我创建一个图表。创建图表后，我的 DFS class 运行 通过遍历为 .txt 文件提供一个或所有解决方案 submitted.I 最近改变了我的 Maze class 至于它 运行 更有效但是我被抛出错误并且数据正在解析到我的 DFS 以输出。我的Mazeclass如下：
import java.io.*;
import java.util.*;
public class Maze {
private final Map<Integer, Set<Integer>> adjList = new HashMap<>();
/**
* The main constructor that takes a String for reading maze file.
*
* @param file
*/
public Maze(File file) throws FileNotFoundException {
try (Scanner scan = new Scanner(file)) {
while (scan.hasNextInt()) {
int node1 = scan.nextInt();
int node2 = scan.nextInt();
this.connect(node1, node2);
this.connect(node2, node1);
}
}
}
/**
* Makes a unidirectional connection from node1 to node2.
*/
private void connect(int node1, int node2) {
if (!this.adjList.containsKey(node1)) {
this.adjList.put(node1, new HashSet<Integer>());
}
this.adjList.get(node1).add(node2);
}
/**
* Returns a human-readable description of the adjacency lists.
*/
public String toString() {
StringBuilder s = new StringBuilder();
for (Map.Entry<Integer, Set<Integer>> adj : this.adjList.entrySet()) {
int from = adj.getKey();
Set<Integer> to = adj.getValue();
s.append(from).append(" connected to ").append(to).append('\n');
}
return s.toString();
}
/**
* Returns the set of nodes connected to a particular node.
*
* @param node - the node whose neighbors should be fetched
*/
public Iterable<Integer> getadjList(int node) {
return Collections.unmodifiableSet(adjList.get(node));
}
/**
* Demonstration of file reading.
*/
public static void main(String[] args) throws FileNotFoundException {
System.err.print("Enter File: ");
Scanner scanFile = new Scanner(System.in);
String file = scanFile.nextLine();
Maze m = new Maze(new File(file));
System.out.println(m);
}
}
我的 DFS 看起来也是这样。
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.Stack;
public class DFS {
//starting node, the route to the next node, has node been visited
private int startNode;
private int[] route;
private boolean[] visited;
// 2 main arguments - Maze File & user input
public DFS(Maze maze, int inputInt) {
int startNode = 0;
int goalNode = 1;
route = new int[maze.node];
visited = new boolean[maze.node];
//Takes user's input and runs desired function
if(inputInt == 1){
findOne(maze, startNode, goalNode);
}
else if (inputInt == 2){
findAll(maze, startNode, goalNode);
}
else {
System.out.println("input invalid. No Solution Returned");
}
}
//Put path to goal in the stack
public Stack<Integer> route(int toGoalNode) {
if (!visited[toGoalNode]) {
return null;
}
Stack<Integer> pathStack = new Stack<Integer>();
for (int routeGoalNode = toGoalNode; routeGoalNode != startNode; routeGoalNode = route[routeGoalNode]) {
pathStack.push(routeGoalNode);
}
pathStack.push(startNode);
reverseStack(pathStack);
return pathStack;
}
//Reverse the stack
public void reverseStack(Stack<Integer> stackToBeReverse) {
if (stackToBeReverse.isEmpty()) {
return;
}
int bottom = popBottomStack(stackToBeReverse);
reverseStack(stackToBeReverse);
stackToBeReverse.push(bottom);
}
//Pop the bottom of the stack
private int popBottomStack(Stack<Integer> stackToBeReverse) {
int popTopStack = stackToBeReverse.pop();
if (stackToBeReverse.isEmpty()) {
return popTopStack;
} else {
int bottomStack = popBottomStack(stackToBeReverse);
stackToBeReverse.push(popTopStack);
return bottomStack;
}
}
//performs DFS and unsets visited to give the result of all paths
private void findAll(Maze maze, int node, int goal) {
visited[node] = true;
if(node == goal) {
printPath(goal);
} else {
for (int con : maze.getadjList(node)) {
if (!visited[con]) {
route[con] = node;
findAll(maze, con, goal);
}
}
}
visited[node] = false;
}
//performs DFS and maintains visited marker giving only one path
private void findOne(Maze maze, int node, int goal) {
visited[node] = true;
for (int con : maze.getadjList(node)) {
if (!visited[con]) {
route[con] = node;
findOne(maze, con, goal);
}
}
}
//Traverse the connections to the goal and print the path taken
public void printPath( int toGoal) {
int goalNode = 1;
if (visited[toGoal]) {
System.out.println("Completed Path: ");
for (int t : route(toGoal)) {
if (t == toGoal) {
System.out.print(t);
} else {
System.out.print(t + " -> ");
}
}
System.out.println();
}
}
public static void main(String[] args) throws FileNotFoundException {
Scanner scanFile = new Scanner(System.in);
int goalNode = 1;
System.out.print("Enter maze file: ");
String file = scanFile.nextLine();
Maze maze = new Maze(new File(file));
Scanner scanInt = new Scanner(System.in);
System.out.print("Enter desired feedback (1 = one soultion, 2 = all): ");
int inputInt = scanInt.nextInt();
// maze.toString();
System.out.println(maze);
DFS dfs = new DFS(maze, inputInt);
dfs.printPath(goalNode);
}
}
我已经查看了一段时间，无法弄清楚为什么要解析和使用数据。我在这里和那里改变了一些东西，但抛出了更多的错误。他们特别说
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
at DFS.findOne(DFS.java:90)
at DFS.<init>(DFS.java:22)
at DFS.main(DFS.java:127)
参考代码行：
visited[node] = true;
findOne(maze, startNode, goalNode);
DFS dfs = new DFS(maze, inputInt);
现在我基本上相信没有通过任何论点，如果有人能指出问题并帮助我解决问题，将不胜感激。再次感谢
编辑:: Maze class
import java.io.*;
import java.util.*;
public class Maze {
static Set<Integer> Nodes = new HashSet<Integer>();
List<Integer>[] conList;
int node; //declaring value for my nodes.
int con; // declaring a connection
//Constructor takes an int parameter to read through the list of corresponding nodes
Maze(int node) {
this.node = node;
this.con = 0;
conList = (List<Integer>[]) new List[node];
for (int index = 0; index < node; index++) {
conList[index] = new LinkedList<Integer>();
}
}
//Constructor that takes a String of the maze file
public Maze(String mazeFile) {
this(nodeSize(mazeFile));
Scanner scan;
try {
//Creates a scanner for reading the file and loops through linking the nodes to their connections.
scan = new Scanner(new File(mazeFile));
while (scan.hasNextInt()) {
int firstNode = scan.nextInt();
int secondNode = scan.nextInt();
addCon(firstNode, secondNode);
}
} catch (FileNotFoundException ex) {
System.out.println("File Not Found.");
}
}
/*Takes String parameter which is the name of the maze file.
* Method designed to return the the size of the set of nodes
*/
public static int nodeSize(String mazeFile) {
Scanner scanNodeSize;
try {
scanNodeSize = new Scanner(new File(mazeFile));
//while scan has more int's left repeat.
while (scanNodeSize.hasNextInt()) {
int firstNode = scanNodeSize.nextInt();
int secondNode = scanNodeSize.nextInt();
Nodes.add(firstNode);
Nodes.add(secondNode);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return Nodes.size();
}
//Method designed to connect the first and second nodes
private void addCon(int firstNode, int secondNode) {
con++;
conList[firstNode].add(secondNode);
conList[secondNode].add(firstNode);
}
//outputs the nodes and their connection's (#remove later?)
public void print() {
for (int n = 0; n < node; n++) {
System.out.print(n + " connected to ");
for (int w : conList[n]) {
System.out.print(w + " ");
}
System.out.println();
}
}
//method returns a list, enabling nodes to be easily accessible.
public Iterable<Integer> getconList(int nodes) {
return conList[nodes];
}
}
您在 0 处遇到索引越界异常。这会让您认为数组未正确初始化。您使用 maze.node 初始化 visited[] 数组，但是在您的代码中我们看不到这个节点变量所在的位置。如果你想让它 运行 可用，你需要给 maze.node 一个合适的值。
*编辑 - 我上面的答案不再适用，因为我们有你以前的迷宫 class 这解释了为什么代码不会 运行.
当前状态下的代码有很多问题，所以我会尝试在这里给你一些指导：
您创建迷宫的新方法是从文件中读取并连接 2 个点并将它们存储在地图中。这样做的问题是您不能只获取下一个元素，因为您必须拥有获取元素的密钥。要解决此问题，您应该使用不同的数据结构。
public DFS(Maze maze, int inputInt) {
int startNode = 0;
int goalNode = 1;
route = new int[maze.node]; //!!! maze.node isn't a thing anymore
visited = new boolean[maze.node]; //!!! maze.node isn't a thing anymore
您可以看到您正在尝试访问 maze.node，它曾经是 Maze 的一个变量。它不再是。您需要找到一种从 Maze 获取节点的新方法。为此，您需要以不同的方式从数据结构中获取节点：
public DFS(Maze maze, int inputInt) {
int startNode = 0;
int goalNode = 1;
route = new int[maze.adjList.getNode()];
visited = new boolean[maze.adjList.getNode()];
对于邻接表的不同数据结构，您有很多选择，但诸如此类：
http://theoryofprogramming.com/adjacency-list-in-java/
会给你一个不错的起点。