【发布时间】：2010-12-24 21:41:02
【问题描述】：
我正在使用这种方法在这个自动机模拟器上从一个状态移动到下一个状态：
public void processString (String string){
StringBuilder stepString= new StringBuilder (string);
int actualStateIntIndex;
System.out.println("THE FOUND INITIAL ONE IS "+ theInitialStateIntIndex);
State firstState = allStates.get(theInitialStateIntIndex);
actualState = firstState;
while (stepString.length()>0){
Character characterToProcess = stepString.charAt(0);
stepString.deleteCharAt(0);
State nextState;
nextState = ((State)actualState.get(characterToProcess)); // pasa al siguiente State
actualState = nextState;
actualStateIntIndex=allStates.indexOf(actualState);
System.out.println("the actual state for " + stepString + " is " + actualStateIntIndex);
if ((actualState.isFinal==true) && (stepString.length()==0))
{
System.out.println("THE STRING " + string + " IS ACCEPTED AT STATE " + actualStateIntIndex );
}
else if (stepString.length()==0 && (actualState.isFinal==false)){
System.out.println("THE STRING " + string + " IS REJECTED AT STATE " + actualStateIntIndex);
}
}
}
这里：
State nextState;
nextState = ((State)actualState.get(characterToProcess));
我可能做错了什么，但我不明白。
自动机总是卡在状态 0，虽然 StringBuilder 正在正确处理，为什么？
这是完整的代码：
package afd;
import java.io.*;
import java.util.*;
/**
*
* @author Administrator
*/
public class Main {
/**
* @param args the command line arguments
*/
public static void main(String[] args) throws IOException {
// TODO code application logic here
FileReader fr = new FileReader("E://Documents and Settings//Administrator//My Documents//NetBeansProjects//AFD//src//afd//dfa.in");
BufferedReader br = new BufferedReader(fr);
String firstLine= br.readLine();
String [] firstLineSplitted = firstLine.split(" ");
/*debug*/
//System.out.println("firstLine is " + firstLine);
int numberOfTestCases = Integer.parseInt(firstLine);
for (int indexOfTestCases =0; indexOfTestCases < numberOfTestCases; indexOfTestCases++ ){
int aux;
System.out.println("Case Number " + (aux = indexOfTestCases+1));
String caseStartLine = br.readLine();
/*debug*/
//System.out.println("caseStarLine is " + caseStartLine);
String [] caseStartLineSplitted = caseStartLine.split(" ");
int numberOfStates;
int numberOfAlphabetSymbols;
int numberOfFinalStates;
numberOfStates = Integer.parseInt(caseStartLineSplitted[0]);
numberOfAlphabetSymbols = Integer.parseInt(caseStartLineSplitted[1]);
numberOfFinalStates = Integer.parseInt(caseStartLineSplitted[2]);
Automaton automaton = new Automaton();
automaton.setAllStates(numberOfStates);
// automaton.size = numberOfStates;
// automaton.numberOfAlphabetSymbols = numberOfAlphabetSymbols;
// automaton.numberOfFinalStates = numberOfFinalStates;
//Automaton a = new Automaton(numberOfStates);
String alphabetLine = br.readLine();
System.out.println("alphabetLine is " + alphabetLine);
automaton.setAlphabet (alphabetLine);
// automaton.alphabetSymbols =new StringBuffer(alphabetLine);
for (int indexOfStates = 0; indexOfStates < numberOfStates; indexOfStates++){
String transitionsLine = br.readLine();
/*debug*/
System.out.println("for the state " + indexOfStates + " transitionsLine is " + transitionsLine);
automaton.setTransitions(indexOfStates,transitionsLine);
/*String [] ijLineSplitted = ijLine.split(" ");
int i = Integer.parseInt(ijLineSplitted[0]);
int j = Integer.parseInt(ijLineSplitted[1]);
*/
}
String finalStatesLine = br.readLine();
/*debug*/
System.out.println("finalStatesLine is " + finalStatesLine);
String finalStatesLineSplitted [] = finalStatesLine.split(" ");
automaton.markFinalStates(finalStatesLineSplitted);
String initialStateAndNumberOfStringsLine = br.readLine();
/*debug*/
//System.out.println("initialStateAndNumberOfStringsLine is " +initialStateAndNumberOfStringsLine);
String [] splittedInitialStateLine = initialStateAndNumberOfStringsLine.split(" ");
int initialState = Integer.parseInt(splittedInitialStateLine[0]);
int numberOfStrings = Integer.parseInt(splittedInitialStateLine[1]);
automaton.markInitialState(initialState);
for (int stringIndex =0; stringIndex<numberOfStrings; stringIndex++){
String stringToProcess = br.readLine();
/*debug*/
System.out.println("stringToProcess is " + stringToProcess);
automaton.processString(stringToProcess);
}
}
}
}
class State extends HashMap<Character, State>{
boolean isFinal;
boolean isInitial;
int stateId;
State () {
isInitial=false;
isFinal = false;
}
public boolean equals (Object o){
boolean isEqual = false;
State compare = (State)o;
if ((compare.stateId)==this.stateId)
{
return true;
}
return isEqual;
}
public int hashCode() {
int theHashCode = stateId%7;
return theHashCode;
}
}
class Automaton{
List <State> allStates;
//private List<State> finalStates;
int theInitialStateIntIndex;
State actualState;
char [] alphabet;
Automaton() {
allStates = new ArrayList<State>();
}public void setAllStates (int numberOfStates) {
for (int i =0; i <numberOfStates; i++) {
State newState = new State();
newState.stateId = i;
allStates.add(newState);
}
}
public void setAlphabet (String alphabetLine){
alphabet = alphabetLine.toCharArray();
}
public void markFinalStates (String [] finalStates){
for (int index =0; index<finalStates.length; index++) {
int aFinalStateId = Integer.parseInt(finalStates[index]);
State aFinalState = allStates.get(aFinalStateId);
aFinalState.isFinal = true;
allStates.add(aFinalStateId, aFinalState);
/*DEBUG*/
aFinalState = allStates.get(aFinalStateId);
if ((aFinalState.isFinal)==true)
System.out.println("THE STATE " + aFinalStateId + " IS MARKED AS FINAL");
}
}
public void markInitialState (int initialStateId) {
State theInitialState = allStates.get(initialStateId);
theInitialState.isInitial=true;
allStates.add(initialStateId, theInitialState);
theInitialStateIntIndex = initialStateId;
/*DEBUG*/
System.out.println("THE INITIAL STATE ID IS " + initialStateId);
theInitialState = allStates.get(initialStateId);
if ((theInitialState.isInitial)==true)
System.out.println("THE STATE " + initialStateId + " IS MARKED AS INITIAL");
}
public void setTransitions(int stateId, String transitionsLine){
State theOneToChange = allStates.get(stateId);
String [] statesToReachStringSplitted = transitionsLine.split(" ");
for (int symbolIndex=0; symbolIndex<statesToReachStringSplitted.length;symbolIndex++){
int reachedState= Integer.parseInt(statesToReachStringSplitted[symbolIndex]);
theOneToChange.put(alphabet[symbolIndex],allStates.get(reachedState));
System.out.println("THE STATE " + stateId + " REACHES THE STATE " + reachedState + " WITH THE SYMBOL " + alphabet[symbolIndex]);
}
allStates.add(stateId, theOneToChange);
}
public int findInitialState(){
int index =0;
cycle: for (; index<allStates.size(); index++){
State s = allStates.get(index);
if (s.isInitial==true) {
break cycle;
}
} return index;
}
public void processString (String string)
{
StringBuilder stepString= new StringBuilder (string);
int actualStateIntIndex;
System.out.println("THE FOUND INITIAL ONE IS "+ theInitialStateIntIndex);
State firstState = allStates.get(theInitialStateIntIndex);
actualState = firstState;
while (stepString.length()>0){
Character characterToProcess = stepString.charAt(0);
stepString.deleteCharAt(0);
State nextState;
nextState = ((State)actualState.get(characterToProcess)); // pasa al siguiente State
actualState = nextState;
actualStateIntIndex=allStates.indexOf(actualState);
System.out.println("the actual state for " + stepString + " is " + actualStateIntIndex);
if ((actualState.isFinal==true) && (stepString.length()==0))
{
System.out.println("THE STRING " + string + " IS ACCEPTED AT STATE " + actualStateIntIndex );
}
else if (stepString.length()==0 && (actualState.isFinal==false)){
System.out.println("THE STRING " + string + " IS REJECTED AT STATE " + actualStateIntIndex);
}
}
}
}
这是输入文件：
4
3 2 1
ab
1 0
2 0
2 0
2
0 3
abaa
aab
aba
3 3 2
ade
0 1 2
1 2 0
2 1 0
1 2
2 2
a
de
3 2 1
ab
1 0
2 0
2 0
2
0 3
abaa
aab
aba
3 3 2
ade
0 1 2
1 2 0
2 1 0
1 2
2 2
a
de
编辑：这里我将解释这个输入文件的格式
第一行代表测试用例的数量。
每个测试用例以 3 个整数开头，第一个是自动机的状态数，接下来是字母表中的符号数，然后是最终状态数。
下一行是字母表。符号一起出现。
然后，行数等于描述转换函数的状态数。这组线的第一行表示自动机 (qo) 中第一个状态的转换函数，第一个元素表示当字母表中的第一个符号进入该状态时达到的状态，依此类推。我无法从原始问题陈述中理解这一点。这是我看到的最简单的方法：
线条：
1 0
2 0
2 0
等于：
AlphabetSymbol0 AlphabetSymbol1
State0 State1 State0
State1 State2 State0
State2 State2 State0
然后有一行说明自动机的最终状态。
然后是一行，说明哪个是初始状态以及将出现多少输入字符串。
然后是输入字符串的行。
这个程序的输出应该是：
C
ase Number 1
alphabetLine is ab
for the state 0 transitionsLine is 1 0
THE STATE 0 REACHES THE STATE 1 WITH THE SYMBOL a
THE STATE 0 REACHES THE STATE 0 WITH THE SYMBOL b
for the state 1 transitionsLine is 2 0
THE STATE 1 REACHES THE STATE 2 WITH THE SYMBOL a
THE STATE 1 REACHES THE STATE 0 WITH THE SYMBOL b
for the state 2 transitionsLine is 2 0
THE STATE 2 REACHES THE STATE 2 WITH THE SYMBOL a
THE STATE 2 REACHES THE STATE 0 WITH THE SYMBOL b
finalStatesLine is 2
THE STATE 2 IS MARKED AS FINAL
THE INITIAL STATE ID IS 0
THE STATE 0 IS MARKED AS INITIAL
stringToProcess is abaa
THE FOUND INITIAL ONE IS 0
the actual state for baa is 0
the actual state for aa is 0
the actual state for a is 0
the actual state for is 0
**THE STRING abaa IS ACCEPTED AT STATE 2**
stringToProcess is aab
THE FOUND INITIAL ONE IS 0
the actual state for ab is 0
the actual state for b is 0
the actual state for is 0
**THE STRING aab IS REJECTED AT STATE 0**
stringToProcess is aba
THE FOUND INITIAL ONE IS 0
the actual state for ba is 0
the actual state for a is 0
the actual state for is 0
**THE STRING aba IS ACCEPTED AT STATE 1**
Case Number 2
alphabetLine is ade
for the state 0 transitionsLine is 0 1 2
THE STATE 0 REACHES THE STATE 0 WITH THE SYMBOL a
THE STATE 0 REACHES THE STATE 1 WITH THE SYMBOL d
THE STATE 0 REACHES THE STATE 2 WITH THE SYMBOL e
for the state 1 transitionsLine is 1 2 0
THE STATE 1 REACHES THE STATE 1 WITH THE SYMBOL a
THE STATE 1 REACHES THE STATE 2 WITH THE SYMBOL d
THE STATE 1 REACHES THE STATE 0 WITH THE SYMBOL e
for the state 2 transitionsLine is 2 1 0
THE STATE 2 REACHES THE STATE 2 WITH THE SYMBOL a
THE STATE 2 REACHES THE STATE 1 WITH THE SYMBOL d
THE STATE 2 REACHES THE STATE 0 WITH THE SYMBOL e
finalStatesLine is 1 2
THE STATE 1 IS MARKED AS FINAL
THE STATE 2 IS MARKED AS FINAL
THE INITIAL STATE ID IS 2
THE STATE 2 IS MARKED AS INITIAL
stringToProcess is a
THE FOUND INITIAL ONE IS 2
the actual state for is 0
**THE STRING a IS ACCEPTED AT STATE 2**
stringToProcess is de
THE FOUND INITIAL ONE IS 2
the actual state for e is 0
the actual state for is 0
**THE STRING de IS REJECTED AT STATE 0**
我错了所有用粗体写的行。
我明白了：
Case Number 1
THE STRING abaa IS ACCEPTED AT STATE 0
THE STRING aab IS ACCEPTED AT STATE 0
THE STRING aba IS ACCEPTED AT STATE 0
Case Number 2
THE STRING a IS ACCEPTED AT STATE 0
THE STRING de IS ACCEPTED AT STATE 0
我的自动机接受一切并卡在状态 0，为什么？
【问题讨论】：
-
您提供的代码无法编译...有些东西丢失了。但是，你能告诉我有多少个状态，stateID 的值是否重要，或者它可以是什么？
-
已修复。每个测试用例有3个状态，有两个测试用例。