java 水题练手汇总

 1 import java.util.*; 
 2 import java.awt.*;
 3 import java.math.*;
 4 
 5 public class Main {
 6     
 7     public static void main(String args[]) {
 8      Scanner cin=new Scanner(System.in);
 9      int n, i;
10      int f[] = new int[35];
11      f[0] = 0;
12      f[1] = 1;
13      f[2] = 2;
14      f[3] = 3;
15      for(i = 4; i < 31; i ++)
16          f[i] = f[i-1] + f[i-2] + f[i-3];
17      while(cin.hasNext())  //多组
18      {
19          n  = cin.nextInt();
20          System.out.println(f[n]);
21      }
22     }
23 }