Submission #156186

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Source Code Expand

package q2;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigDecimal;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = null;
		try {
			br = new BufferedReader(new InputStreamReader(System.in));
			for (String line = br.readLine(); line != null; line = br.readLine()) {
				int n = Integer.parseInt(line);
				if (n == 1 || n == 2) {
					System.out.println(0);
				} else if (n == 3) {
					System.out.println(1);
				} else {
					// 愚直に求めます
					BigDecimal a1 = BigDecimal.ZERO;
					BigDecimal a2 = BigDecimal.ZERO;
					BigDecimal a3 = BigDecimal.valueOf(1);
					BigDecimal tri = BigDecimal.ZERO;
					for (int i = 0; i < n - 3; i++) {
						// 全部足したのがトリボナッチです
						tri = a1.add(a2).add(a3);
						// １つずらします
						a1 = a2;
						a2 = a3;
						a3 = tri;
					}
					System.out.println(tri.remainder(BigDecimal.valueOf(10007)));
				}
			}
		} finally {
			if (br != null) {
				try {
					br.close();
				} catch (IOException e) {
				}
			}
		}
	}
}

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