HDU-5973 Game of Taking Stones

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【HDU-5973 Game of Taking Stones】

题意：标准的威佐夫博弈, 只不过数据范围特别大, 要使用高精度. 威佐夫博弈详情见
分析：只要根据威佐夫博弈的条件进行判断即可, 高精度需要计算sqrt(5), 这里使用二分求解.

import java.math.BigDecimal;
import java.util.Scanner;

public class Main {
	
	public static BigDecimal getGoldNumber (){
		BigDecimal eps = new BigDecimal("0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001");
		BigDecimal l = BigDecimal.valueOf(2);
		BigDecimal r = BigDecimal.valueOf(3);
		BigDecimal mid, pre = BigDecimal.valueOf(5);
		//get sqrt(5.0)
		while (l.multiply(l).subtract(pre).abs().compareTo(eps) > 0) {
			mid = l.add(r).divide(BigDecimal.valueOf(2));
			if (mid.multiply(mid).compareTo(pre) < 0) l = mid;
			else r = mid;
		}
		BigDecimal b = BigDecimal.ONE.add(l).divide(BigDecimal.valueOf(2));
		return b;
	}
	
	public static String toInt(String s) {
		String ans = "";
		for (int i = 0; i < s.length(); i++) {
			if (s.charAt(i) == '.') break;
			else {
				ans += s.charAt(i);
			}
		}
		return ans;
	}
	public static void main (String args[]) {
		Scanner sc = new Scanner(System.in);
		BigDecimal a, b;
		BigDecimal bt = getGoldNumber();
		while (sc.hasNext()){
			a = sc.nextBigDecimal();
			b = sc.nextBigDecimal();
			
			if (a.compareTo(b) > 0) {
				BigDecimal c;
				c = a;
				a = b;
				b = c;
			}
			String p = toInt(bt.multiply(b.subtract(a)).toString());
			String q = toInt(a.toString());
			if (p.compareTo(q) == 0) System.out.println("0");
			else System.out.println("1");
		}
		sc.close();
	}
}