Code Jam 2013, Problem C (large input 1) http://code.google.com/codejam/contest/2270488/dashboard#s=p2

C2.java

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

public class C2 {
	static Scanner in;
	static BufferedWriter out;
	long[] palin = new long[40];
	
	public static void main(String[] args) throws Exception {
		in = new Scanner(new File("c2.in"));
		out = new BufferedWriter(new FileWriter("c2.out"));
		new C2().run();
		out.close();
	}
	
	void run() throws IOException {
		init();
		int t = in.nextInt();
		
		for(int i=1; i<=t; i++) {
			long a = in.nextLong(), b = in.nextLong();
			int count = 0;
			for (int j=0; j<palin.length; j++) {
				if(palin[j] >= a && palin[j] <= b) {
					count++;
				}
			}
			out.write(String.format("Case #%d: %d%n", i, count));
		}
	}
	
	void init() {
		int j = 0;
		for(long i=1; i<10000003; i++) {
			if(isPalin(i) && isPalin(i * i)) {
				palin[j++] = i * i;
			}
		}
	}
	
	boolean isPalin(long n) {
		if (n < 10) {
			return true;
		}
		String value = String.valueOf(n);
		int size = value.length();
		for (int i = 0, j = size - 1; i < size / 2; i++, j--) {
			if (value.charAt(i) != value.charAt(j)) {
				return false;
			}
		}
		return true;
	}
}