Simple Complete Search

1. Broken Necklace

　　This is my solution to the USACO training problem "beads":

import java.io.*;
import java.util.*;

public class beads {
    public static BufferedReader input;
    public static PrintWriter output;
    public static int len;
    public static String str;
    
    public static boolean same(int i,int j) {
        char a=str.charAt(i), b=str.charAt(j);
        if (a=='w' || b=='w') {
            return true;
        } else {
            return a==b;
        }
    }
    public static boolean diff(int i,int j) {
        char a=str.charAt(i),b=str.charAt(j);
        if (a=='w' || b=='w') {
            return true;
        } else {
            return a!=b;
        }
    }
    public static int searchLeft(int pos) {
        int val = 0;
        for (int i=1;i<len;i++) {
            if (!diff(pos,(pos+len-i)%len)) {
                break;
            } else {
                val++;
            }
        }
        return val;
    }
    public static int searchRight(int pos) {
        int val = 1;
        for (int i=1;i<len;i++) {
            if (!same(pos,(pos+i)%len)) {
                break;
            } else {
                val++;
            }
        }
        return val;
    }
    public static int solve() {
        int val = 0;
        for (int i=0;i<len;i++) {
            // For every bead i whose color is red or blue:
            //        traverse its right side until an opposite color appears;
            //        traverse its left side until a same color shows up
            if (str.charAt(i)=='w') {
                continue;
            }
            int tmp = searchLeft(i);
            tmp += searchRight(i);
            if (tmp>val) {
                val = tmp;
            }
        }
        if (val==0||val>len) {
            // probably all beads are white
            return len;
        } else {
            return val;
        }
    }
    public static void main(String[] args) throws IOException{
        input = new BufferedReader(new FileReader("beads.in"));
        len = Integer.parseInt(input.readLine());
        str = input.readLine();
        input.close();
        output = new PrintWriter(new FileWriter("beads.out"));
        output.println(solve());
        output.close();
    }
}

2. Milking Cows

　　This is my solution to the USACO training problem "milk2":

import java.io.*;
import java.util.*;

public class milk2 {
    // KEEP IT SIMPLE AND STUDPID
    
    public static final int MAX=1000001;
    public static BufferedReader input;
    public static PrintWriter output;
    public static boolean [] busy;
    
    public static void solve(int start,int end) {
        int milk=0, free=0, mkTmp=0, frTmp=0;
        for (int i=start;i<=end;i++) {
            if (busy[i] && mkTmp++==0) {
                if (frTmp>free) {
                    free = frTmp;
                }
                frTmp = 0;
            } else if (!busy[i] && frTmp++==0){
                if (mkTmp>milk) {
                    milk = mkTmp;
                }
                mkTmp = 0;
            }
        }
        output.println(milk+" "+free);
    }
    public static void main(String[] args) throws IOException{
        input = new BufferedReader(new FileReader("milk2.in"));
        int n = Integer.parseInt(input.readLine());
        busy = new boolean [MAX];
        int start=MAX, end=0;
        for (int i=0;i<n;i++) {
            StringTokenizer str = new StringTokenizer(input.readLine());
            int p = Integer.parseInt(str.nextToken());
            if (p<start) {
                start = p;
            }
            int r = Integer.parseInt(str.nextToken());
            if (r>end) {
                end = r;
            }
            for (int j=p;j<r;j++) {
                busy[j] = true;
            }
        }
        input.close();
        output = new PrintWriter(new FileWriter("milk2.out"));
        solve(start,end);
        output.close();
    }
}

3. Calf Flac

　　This is my solution to the USACO training problem "calfflac":

import java.io.*;
import java.util.*;

public class calfflac{
    public static BufferedReader input;
    public static PrintWriter output;
    public static char [] data;
    public static int [] index;
    
    public static boolean isChar(char ch) {
        if (ch>='A' && ch<='Z') {
            return true;
        } else if (ch>='a'&&ch<='z') {
            return true;
        } else {
            return false;
        }
    }
    public static boolean same(int i,int j) {
        char a=data[index[i]];
        char b=data[index[j]];
        return a==b || a==b+32 || a==b-32;
    }
    public static int odd(int pos,int len) {
        int val = 0;
        for (;pos-val>=0 && pos+val<len;val++) {
            if (!same(pos-val,pos+val)) {
                break;
            }
        }
        return val-1;
    }
    public static int even(int pos,int len)  {
        int val;
        for (val=0;pos-val>=0 && pos+val+1<len;val++) {
            if (!same(pos-val,pos+val+1)) {
                break;
            }
        }
        return val-1;
    }
    public static void solve(int len) {
        int max=0, start=0, end=0;
        for (int i=0;i<len;i++) {
            int j = odd(i,len);
            if (max<(j<<1)+1) {
                max = (j<<1)+1;
                start = i-j;
                end = i+j;
            }
        }
        for (int i=0;i<len;i++) {
            int j = even(i,len);
            if (max<(j<<1)+2) {
                max = (j<<1)+2;
                start = i-j;
                end = i+j+1;
            }
        }
        output.println(max);
        for (int i=index[start];i<=index[end];i++) {
            output.print(data[i]);
        }
        output.println();
    }
    public static void main(String[] args) throws IOException  {
        data = new char [20000];
        index = new int [20000];
        input = new BufferedReader(new FileReader("calfflac.in"));
        int pos=0, len=0;
        String line = input.readLine();
        while (line!=null)  {
            for (int i=0;i<line.length();i++) {
                data[pos++] = line.charAt(i);
                if (isChar(line.charAt(i))) {
                    index[len++] = pos-1;
                }
            }
            data[pos++] = '
';
            line = input.readLine();
        }
        input.close();
        output = new PrintWriter(new FileWriter("calfflac.out"));
        solve(len);
        output.close();
    }
}