题解 | #杨辉三角的变形#

import javax.script.ScriptException;
import java.util.Scanner;

public class Main {
  public static void main(String[] args) throws ScriptException {
    Scanner sc = new Scanner(System.in);
    while (sc.hasNextInt()) {
      System.out.println(test(sc.nextInt()));
    }
  }

  public static int test(int x) { // x 行数
    for (int i = 1; i <= x; i++) {
      if (F(x, i) % 2 == 0) {
        return i;
      }
    }
    return -1;
  }

  public static int F(int x, int y) { // x 行数，y位置
    if (y > 2 * x - 1) {
      return 0;
    }
    if (y <= 0) {
      return 0;
    }
    if (x <= 0) {
      return 0;
    }
    if (x == 1) {
      return 1;
    }
    if (y == 1) {
      return 1;
    }
    return F(x - 1, y - 1) + F(x - 1, y - 2) + F(x - 1, y);
  }
}