迅雷亲历面经：笔试+上机+面试（完整JAVA面试题求解大讨论）

public class DFAMap {
	private List<String> arr = new ArrayList<String>();
	private Node rootNode = new Node('R');
	
	private String content = "";
	
	private List<String> words = new ArrayList<String>();   
	private List<String> word = new ArrayList<String>();
	private int a = 0;
	
	public DFAMap() throws Exception {
		FileInputStream in = new FileInputStream(new File("c:\\name.txt"));
		BufferedReader br = new BufferedReader(new InputStreamReader(in));
		String inputLine;
		while ((inputLine = br.readLine()) != null) {
			arr.add(inputLine);
		}
		in.close();
		br.close();
		
		in = new FileInputStream(new File("c:\\story.txt"));
		br = new BufferedReader(new InputStreamReader(in));
		StringBuilder sb = new StringBuilder();
		while ((inputLine = br.readLine()) != null) {
			sb.append(inputLine.trim());
		}
		content = sb.toString();
		in.close();
		br.close();
	}
	
	private void searchWord() {
		char[] chars = content.toCharArray();
		Node node = rootNode;
		while(a<chars.length) {
			node = findNode(node,chars[a]);
			if(node == null) {
				node = rootNode;
				a = a - word.size();
				word.clear();
			} else if(node.flag == 1) {
				word.add(String.valueOf(chars[a]));
				StringBuffer sb = new StringBuffer();
				for(String str : word) {
					sb.append(str);
				}
				words.add(sb.toString());
				a = a - word.size() + 1;
				word.clear();
				node = rootNode;
			} else {
				word.add(String.valueOf(chars[a]));
			}
			a++;
		}
	}
	
	private void createTree() {
		for(String str : arr) {
			char[] chars = str.toCharArray();
			if(chars.length > 0)
				insertNode(rootNode, chars, 0);
		}
	}
	
	private void insertNode(Node node, char[] cs, int index) {
		Node n = findNode(node, cs[index]);
		if(n == null) {
			n = new Node(cs[index]);
			node.nodes.put(String.valueOf(n.c), n);
		}
		
		if(index == (cs.length-1))
			n.flag = 1;
			
		index++;
		if(index<cs.length)
			insertNode(n, cs, index);
	}
	
	private Node findNode(Node node, char c) {
		return node.nodes.get(String.valueOf(c));
	}
	
	public static void main(String[] args) throws Exception {
		DFAMap dfa = new DFAMap();
		dfa.createTree();
		long time = System.nanoTime();
		dfa.searchWord();
		System.out.println(System.nanoTime()-time);
		
		int count = 0;
		for(String word : dfa.words) {
			if("鏈卞厓鐠�".equals(word)) {
				++count;
			}
		}
		System.out.println("鏈卞厓鐠嬶細"+count);
	}
	
	
	private static class Node {
		public char c;
		public int flag; //1锛氳〃绀虹粓缁擄紝0锛氬欢缁�
		public Map<String,Node> nodes = new HashMap<String,Node>();
		
		public Node(char c) {
			this.c = c;
			this.flag = 0;
		}
		
		public Node(char c, int flag) {
			this.c = c;
			this.flag = flag;
		}
	}
}

diaodou 写道

C 2) 可以用这个简单方法。
上机题是一样的方法，开个256的数组，count[256]，表示每个字母，数字等的出现次数。
class Remove{
　public static void main(String args[]) {
　　String str="6sabcsssfsfs33；
    boolean removeChars[256] = {true};
    removeChars['a'] = false;
    removeChars['b'] = false;
    removeChars['3'] = false;
　　StringBuffer sb = new StringBuffer();
    for (char ch: str) {
        if (!removeChars[ch]) sb.append(ch);
    }
    String result = sb.toString();
　}
}

高人啊，应该就是这个方法了

太强了 我看了好久才看懂  看来菜鸟和大牛区别就是不同……