Googole Code Jam

a.java

import java.util.*;
import java.lang.*;

public class Main {
    static int doit(String ps, int fsiz) {
	int len = ps.length();
	boolean bs[] = new boolean[len];

	for (int i = 0; i < len; i++) {
	    bs[i] = ((ps.charAt(i) == '+')?true:false);
	}

	int cnt = 0;
	for (int i = 0; i + fsiz <= len; i++) {
	    if (bs[i]) continue;

	    cnt++;
	    for (int j = 0; j < fsiz; j++) {
		bs[i+j] = !bs[i+j];
	    }
	}

	for (int i = 0; i < len; i++) {
	    if (!bs[i]) {
		return -1;
	    }
	}

	return cnt;
    }
    
    public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);

	int t = sc.nextInt();

	for (int i = 0; i < t; i++) {
	    int result = doit(sc.next(), sc.nextInt());

	    System.out.printf("Case #%d: ", i + 1);
	    if (result >= 0) {
		System.out.println("" + result);
	    } else {
		System.out.println("IMPOSSIBLE");
	    }
	}
    }
}

b.java

import java.util.*;
import java.lang.*;

public class Main {
    static long toLong(int[] ds) {
	long n = 0;
	
	for (int i = 0; i < ds.length; i++)  {
	    n *= 10;
	    n += ds[i];
	}

	return n;
    }

    static long findMinTidy(int[] ds, int c) {
	if (c == 0 || (ds[c] != 0 && ds[c-1] <= ds[c] - 1)) {
	    ds[c]--;
	    return toLong(ds);
	} else {
	    ds[c] = 9;
	    return findMinTidy(ds, c - 1);
	}
    }

    static long doit (String str) {
	int len = str.length();
	int[] ds = new int[len];

	for (int i = 0; i < len; i++) {
	    ds[i] = Character.getNumericValue(str.charAt(i));
	}

	for (int i = 0; i < len - 1; i++) {
	    if (ds[i] > ds[i+1]) {
		for (int j = i+1; j < len; j++) {
		    ds[j] = 9;
		}

		return findMinTidy(ds, i);
	    }
	}

	return Long.parseLong(str);
    }
    
    public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);

	int t = sc.nextInt();

	for (int i = 0; i < t; i++) {
	    System.out.printf("Case #%d: %d\n", i+1, doit(sc.next()));
	}
    }
}

c.java

import java.util.*;
import java.lang.*;

class Pair {
    public long l, r;
    public Pair(long l, long r) {
	this.l = l;
	this.r = r;
    }
}

public class Main {
    static long dmx (long a) {return a / 2;}
    static long dmn (long a) {return (a - 1) / 2;}

    static Pair rec(long m, long l, long nm, long nl, long k) {
	if (nm >= k) {
	    return new Pair(dmx(m), dmn(m));
	    
	} else if (nm + nl >= k) {
	    return new Pair(dmx(l), dmn(l));
	    
	} else if (m % 2 == 1) {
	    return rec(dmx(m), dmn(l), nm * 2 + nl, nl, k - (nm + nl));

	} else {
	    return rec(dmx(m), dmn(l), nm, nm + nl * 2, k - (nm + nl));
	}
    }

    static Pair doit(long n, long k) {
	return rec(n, n-1, 1, 0, k);
    }
    
    public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);

	int t = sc.nextInt();
	for (int i = 0; i < t; i++) {
	    Pair result = doit(sc.nextLong(), sc.nextLong());
	    System.out.printf("Case #%d: %d %d\n", i+1, result.l, result.r);
	}
    }
}