JAVA蓝桥杯黄金分割数，涉及到bigdecimal

 import java.math.BigDecimal;

 public class test {

     public static void main(String[] args) {
         BigDecimal one, ans;

         ans = one = BigDecimal.ONE;

         for (int i = 0; i < 1000; i++) {
             ans = one.add(ans);

             ans = one.divide(ans, 200, BigDecimal.ROUND_HALF_UP);
             System.out.println(ans);

         }

         System.out.println(ans.setScale(100, BigDecimal.ROUND_HALF_UP));
     }

 }

bigdecimal.round_half_up