USACO试题beads的两种解法

package Karl.Water;



/*

LANG: JAVA

TASK: beads

*/





import java.io.BufferedReader;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.PrintWriter;

import java.util.LinkedList;



public class beads {



	/**

	 * @param args

	 */

	public static void main(String[] args) {

		// TODO Auto-generated method stub

		try {

			BufferedReader br = new BufferedReader(new FileReader("beads.in"));

			PrintWriter pw = new PrintWriter (new FileWriter("beads.out"));

			

			int length = Integer.parseInt(br.readLine());

			String temp = br.readLine();

			LinkedList<Character> necklace = new LinkedList<Character>();

			for (int i=0;i<length;i++) {

				necklace.add(temp.charAt(i));

			}

			

			int max = 0;

			for (int i=0;i<length;i++) {

				char remove = necklace.removeFirst();

				char first = necklace.getFirst();

				int position = 0;

				necklace.addLast(remove);

				

				int result = 0;

				boolean allW = false;

				if (necklace.getFirst()=='w'){

					int end1 = find(necklace,0,length,0); 

					result = end1 + 1;

					if (end1<necklace.size()-1){

						int end2 = find (necklace,end1+1,length,0);

						first = necklace.get(end2);

						position = end2;

						result = result + end2 - end1;

					}else {

						allW = true;

					}

				} else {

					int end = find(necklace,0,length,0);

					position = end ;

					result = result + end + 1;

				}

				if (!allW){

					if (necklace.getLast()=='w') {

						int end1 = find(necklace, length-1,position,1);

						int end2 = find(necklace,end1-1,position,1);

						

						if (necklace.get(end2)==first){

							result = result ;

						}else {

							result = result + length - end1;

							result = result + end1 - end2 ;

						}

					}else {

						if (necklace.getLast()==first){

							result = result; 

						}else {

							int end = find(necklace,length-1,position,1);

							result = result + length - end ;	

						}

					}

				}

				if (result >=max){

					max = result;

				}

			}

			pw.println(max);

			pw.close();

			br.close();

		} catch (Exception e) {

			// TODO Auto-generated catch block

			e.printStackTrace();

		}

	}

	

	public static int find(LinkedList<Character> necklace,int startPoint ,int endPoint,int direction){

		if (direction ==0 ){

			int i=startPoint+1;

			for (;i<=endPoint-1;i++){

				if (necklace.get(i)!=necklace.get(startPoint)&&necklace.get(i)!='w'){

					break;

				}

			}

			return i-1;

		} else {

			int i=startPoint-1;

			for (;i>=endPoint+1;i--){

				if (necklace.get(i)!=necklace.get(startPoint)&&necklace.get(i)!='w'){

					break;

				}

			}

			return i+1;

		}

	}



}

package Karl.Water;



import java.io.BufferedReader;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.ArrayList;

import java.util.List;



public class beads1 {

	List<Integer> list = new ArrayList<Integer>();

	public int judge(String s){

		if(s.charAt(0)=='w'){

			return judgeE(s);

		}else{

			return judgeB(s);

		}

	}

	public int judgeE(String s){

		int result=0;

		int j=0;

		char c=s.charAt(s.length()-1);

		for(int k=s.length()-1;k>0;k--){

			j++;

			if(c!=s.charAt(k-1)&&s.charAt(k-1)!='w'){

				list.add(j);

				System.out.println(j);

				j=0;

				c=s.charAt(k-1);

			}

		}

		int h = 0;

		for(int k=0;k<s.length()-1;k++){

			if(s.charAt(k)==s.charAt(k+1)){

				h++;

			}

		}

	//	System.out.println(h+" "+s.length()/2);

		if(h==(s.length()-1)){

			list.add((s.length()/2));

		}

		list.add(0);

		int size = list.size();

		for(int p=0;p<size;p++){

			if(p==size-1){

				result = result>(list.get(p)+list.get(0))?result:(list.get(p)+list.get(0));

			}else{

				result = result>(list.get(p)+list.get(p+1))?result:(list.get(p)+list.get(p+1));

			}

		}

		return result;

	}

	public int judgeB(String s){

		int result=0,f=0;

		int j=0;

		char c=s.charAt(0);

		for(int k=0;k<s.length()-1;k++){

			j++;

			if(c!=s.charAt(k+1)&&s.charAt(k+1)!='w'){

				list.add(j);

				j=0;

				c=s.charAt(k+1);

			}

		}

		int h = 0;

		for(int k=0;k<s.length()-1;k++){

			if(s.charAt(k)==s.charAt(k+1)){

				h++;

			}

		}

	//	System.out.println(h+" "+s.length()/2);

		if(h==(s.length()-1)){

			list.add((s.length()/2));

		}

		list.add(0);

		int size = list.size();

		for(int p=0;p<size;p++){

			if(p==size-1){

				result = result>(list.get(p)+list.get(0))?result:(list.get(p)+list.get(0));

			}else{

				result = result>(list.get(p)+list.get(p+1))?result:(list.get(p)+list.get(p+1));

			}

		}

		return result;

	}

	public static void main(String[] args) throws IOException {

		beads1 b = new beads1();

		BufferedReader br = new BufferedReader(new FileReader("beads.in"));

		PrintWriter pw = new PrintWriter (new FileWriter("beads.out"));

		String s1 = br.readLine();

		String s2 = br.readLine();

		pw.println(b.judge(s2+s2));

		pw.close();

		br.close();

	}

}