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