Levenshtein distance

gistfile1.java

import java.io.*;
import java.util.*;
public class levenshtein_distance{
	public static HashSet[]h=new HashSet[25];
	public static Stack<String>st=new Stack<String>();
	public static HashSet<String>fnl=new HashSet<String>();
	public static void main(String args[]) throws Exception{
		long aa=System.currentTimeMillis();
		InputReader sc=new InputReader(new FileInputStream("in.txt"));
		int i,j;
		for(i=0;i<25;i++) h[i]=new HashSet<String>();
		String a="";
		for(;!sc.isExhausted();){
			a=sc.readLine();
			h[a.length()].add(a);
		}
		String tof="hello";
		st.add(tof);
		while(!st.isEmpty()){
			a=st.pop();
			fnl.add(a);
			addwords(a);
		}
		System.out.println(fnl.size()-1);
		System.out.println((System.currentTimeMillis()-aa)+"ms");
	}
	public static void addwords(String wrd){
		int i,len=wrd.length();
		char z;
		StringBuffer sb;
		String b="";
		for(i=0;i<len;i++){
			sb=new StringBuffer(wrd);
			sb=sb.deleteCharAt(i);b=sb.toString();
			if(h[len-1].contains(b)){
				st.add(b);h[len-1].remove(b);
			}
		}
		for(i=0;i<=len;i++){
			for(z='a';z<='z';z++){
				sb=new StringBuffer(wrd);
				sb=sb.insert(i,z);
				b=sb.toString();
				if(h[len+1].contains(b)){
					st.add(b);h[len+1].remove(b);
				}
			}
		}
		for(i=0;i<len;i++){
			for(z='a';z<='z';z++){
				sb=new StringBuffer(wrd);
				sb.setCharAt(i,z);
				b=sb.toString();
				if(h[len].contains(b)){
					st.add(b);h[len].remove(b);
				}
			}
		}
	}
}
class InputReader {
	private boolean finished = false;

	private InputStream stream;
	private byte[] buf = new byte[1024];
	private int curChar;
	private int numChars;

	public InputReader(InputStream stream) {
		this.stream = stream;
	}

	public int read() {
		if (numChars == -1)
			throw new InputMismatchException();
		if (curChar >= numChars) {
			curChar = 0;
			try {
				numChars = stream.read(buf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (numChars <= 0)
				return -1;
		}
		return buf[curChar++];
	}

	public int peek() {
		if (numChars == -1)
			return -1;
		if (curChar >= numChars) {
			curChar = 0;
			try {
				numChars = stream.read(buf);
			} catch (IOException e) {
				return -1;
			}
			if (numChars <= 0)
				return -1;
		}
		return buf[curChar];
	}

	public int readInt() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		int res = 0;
		do {
			if (c < '0' || c > '9')
				throw new InputMismatchException();
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	public long readLong() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		long res = 0;
		do {
			if (c < '0' || c > '9')
				throw new InputMismatchException();
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	public String readString() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		StringBuffer res = new StringBuffer();
		do {
			res.appendCodePoint(c);
			c = read();
		} while (!isSpaceChar(c));
		return res.toString();
	}

	public static boolean isSpaceChar(int c) {
		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	private String readLine0() {
		StringBuffer buf = new StringBuffer();
		int c = read();
		while (c != '\n' && c != -1) {
			if (c != '\r')
				buf.appendCodePoint(c);
			c = read();
		}
		return buf.toString();
	}

	public String readLine() {
		String s = readLine0();
		while (s.trim().length() == 0)
			s = readLine0();
		return s;
	}

	public String readLine(boolean ignoreEmptyLines) {
		if (ignoreEmptyLines)
			return readLine();
		else
			return readLine0();
	}

	public char readCharacter() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		return (char) c;
	}

	public double readDouble() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		double res = 0;
		while (!isSpaceChar(c) && c != '.') {
			if (c == 'e' || c == 'E')
				return res * Math.pow(10, readInt());
			if (c < '0' || c > '9')
				throw new InputMismatchException();
			res *= 10;
			res += c - '0';
			c = read();
		}
		if (c == '.') {
			c = read();
			double m = 1;
			while (!isSpaceChar(c)) {
				if (c == 'e' || c == 'E')
					return res * Math.pow(10, readInt());
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				m /= 10;
				res += (c - '0') * m;
				c = read();
			}
		}
		return res * sgn;
	}

	public boolean isExhausted() {
		int value;
		while (isSpaceChar(value = peek()) && value != -1)
			read();
		return value == -1;
	}

	public String next() {
		return readString();
	}
}