Set<Character> set=new Hash set
时间: 2024-05-16 12:17:17 浏览: 11
这段代码有一些错误,应该是:
```
Set<Character> set = new HashSet<>();
```
这段代码创建了一个 `HashSet` 对象,并将其赋值给 `set` 变量,同时指定其元素类型为 `Character`。`HashSet` 是 Java 中的一个集合类,它实现了 `Set` 接口,可以用来存储不重复的元素。在这个例子中,我们创建了一个 `HashSet` 来存储字符类型的元素。
相关问题
Java实现NFA转DFA并运行
实现NFA转DFA并运行需要以下步骤:
1. 定义NFA
首先需要定义一个NFA,包括状态集合、起始状态、接受状态、转移函数等。
2. 将NFA转换为DFA
NFA的转换可以使用子集构造法,将NFA中的状态集合转换为DFA中的状态集合,同时计算每个DFA状态的转移函数。
3. 运行DFA
在转换为DFA后,可以使用DFA对输入字符串进行识别。从起始状态开始,按照输入字符串中的字符依次进行转移,当到达一个接受状态时,判断输入字符串是否被识别。
下面是一个简单的Java代码实现NFA转DFA并运行的示例:
```
import java.util.*;
public class NfaToDfa {
private Set<State> nfaStates; // NFA状态集合
private Set<State> dfaStates; // DFA状态集合
private Map<State, Map<Character, Set<State>>> nfaTransitions; // NFA转移函数
private Map<State, Map<Character, State>> dfaTransitions; // DFA转移函数
private State nfaStartState; // NFA起始状态
private Set<State> nfaAcceptStates; // NFA接受状态集合
private State dfaStartState; // DFA起始状态
private Set<State> dfaAcceptStates; // DFA接受状态集合
public NfaToDfa(Set<State> nfaStates, Map<State, Map<Character, Set<State>>> nfaTransitions, State nfaStartState, Set<State> nfaAcceptStates) {
this.nfaStates = nfaStates;
this.nfaTransitions = nfaTransitions;
this.nfaStartState = nfaStartState;
this.nfaAcceptStates = nfaAcceptStates;
this.dfaStates = new HashSet<>();
this.dfaTransitions = new HashMap<>();
this.dfaStartState = null;
this.dfaAcceptStates = new HashSet<>();
}
public void convert() {
// 计算NFA的ε-闭包
Map<State, Set<State>> epsilonClosure = new HashMap<>();
for (State state : nfaStates) {
epsilonClosure.put(state, epsilonClosure(state));
}
// 子集构造法,计算DFA状态集合和转移函数
Set<State> startStates = epsilonClosure(nfaStartState);
dfaStartState = new State(startStates);
dfaStates.add(dfaStartState);
Queue<State> queue = new LinkedList<>();
queue.offer(dfaStartState);
while (!queue.isEmpty()) {
State dfaState = queue.poll();
for (char c = 'a'; c <= 'z'; c++) {
Set<State> nfaStates = new HashSet<>();
for (State state : dfaState.states) {
if (nfaTransitions.containsKey(state) && nfaTransitions.get(state).containsKey(c)) {
nfaStates.addAll(nfaTransitions.get(state).get(c));
}
}
Set<State> closure = new HashSet<>();
for (State state : nfaStates) {
closure.addAll(epsilonClosure.get(state));
}
if (!closure.isEmpty()) {
State newState = new State(closure);
dfaTransitions.computeIfAbsent(dfaState, k -> new HashMap<>()).put(c, newState);
if (!dfaStates.contains(newState)) {
dfaStates.add(newState);
queue.offer(newState);
}
}
}
}
// 计算DFA的接受状态集合
for (State dfaState : dfaStates) {
for (State nfaState : dfaState.states) {
if (nfaAcceptStates.contains(nfaState)) {
dfaAcceptStates.add(dfaState);
break;
}
}
}
}
public boolean accept(String input) {
State currentState = dfaStartState;
for (char c : input.toCharArray()) {
currentState = dfaTransitions.get(currentState).get(c);
if (currentState == null) {
return false;
}
}
return dfaAcceptStates.contains(currentState);
}
private Set<State> epsilonClosure(State state) {
Set<State> closure = new HashSet<>();
Stack<State> stack = new Stack<>();
stack.push(state);
while (!stack.isEmpty()) {
State s = stack.pop();
closure.add(s);
if (nfaTransitions.containsKey(s) && nfaTransitions.get(s).containsKey(null)) {
for (State t : nfaTransitions.get(s).get(null)) {
if (!closure.contains(t)) {
stack.push(t);
}
}
}
}
return closure;
}
private static class State {
private Set<State> states;
public State(Set<State> states) {
this.states = states;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
State state = (State) o;
return Objects.equals(states, state.states);
}
@Override
public int hashCode() {
return Objects.hash(states);
}
}
}
```
使用示例:
```
Set<NfaToDfa.State> nfaStates = new HashSet<>();
NfaToDfa.State nfaStartState = new NfaToDfa.State(Collections.singleton(nfaState1));
Set<NfaToDfa.State> nfaAcceptStates = Collections.singleton(nfaState4);
Map<NfaToDfa.State, Map<Character, Set<NfaToDfa.State>>> nfaTransitions = new HashMap<>();
nfaTransitions.put(nfaState1, Collections.singletonMap('a', Collections.singleton(nfaState2)));
nfaTransitions.put(nfaState2, Collections.singletonMap(null, Collections.singleton(nfaState3)));
nfaTransitions.put(nfaState3, Collections.singletonMap('b', Collections.singleton(nfaState4)));
NfaToDfa nfaToDfa = new NfaToDfa(nfaStates, nfaTransitions, nfaStartState, nfaAcceptStates);
nfaToDfa.convert();
System.out.println(nfaToDfa.accept("ab")); // true
System.out.println(nfaToDfa.accept("abc")); // false
```
把这段代码改为doris的建表语句CREATE TABLE `aa_ccd` ( `ID` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL, `CCDCODE` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `ICNNAME` varchar(107) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `ISDISEASE` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `ENNAME` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `PARENTID` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `YEAR` varchar(4) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `NOTE` varchar(200) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `LEFTSPACE` varchar(10) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `LIMITED` varchar(4) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `LEVEL1` varchar(4) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `LEVEL2` varchar(4) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `LEVEL3` varchar(4) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, `LEVEL4` varchar(4) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL, PRIMARY KEY (`ID`) USING BTREE, INDEX `index1`(`CCDCODE`) USING BTREE, INDEX `index2`(`ICNNAME`) USING BTREE, INDEX `index_yes`(`YEAR`) USING BTREE ) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;
您好!以下是将代码改为Doris建表语句的结果:
CREATE TABLE aa_ccd (
ID VARCHAR(20),
CCDCODE VARCHAR(20),
ICNNAME VARCHAR(107),
ISDISEASE VARCHAR(20),
ENNAME VARCHAR(20),
PARENTID VARCHAR(20),
YEAR VARCHAR(4),
NOTE VARCHAR(200),
LEFTSPACE VARCHAR(10),
LIMITED VARCHAR(4),
LEVEL1 VARCHAR(4),
LEVEL2 VARCHAR(4),
LEVEL3 VARCHAR(4),
LEVEL4 VARCHAR(4)
) DISTRIBUTE BY HASH(ID) BUCKETS 8 PROPERTIES("replication_num"="1");
相关推荐
![gz](https://img-home.csdnimg.cn/images/20210720083447.png)
![zip](https://img-home.csdnimg.cn/images/20210720083736.png)
![zip](https://img-home.csdnimg.cn/images/20210720083736.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![zip](https://img-home.csdnimg.cn/images/20210720083736.png)