[java]Tetranacci

This is a tetranacci algorithm in JAVA version.

It compares two algorithms.

import java.io.PrintWriter;public class Assignment1 {    long tetranacci1(int index){        // index start from 0,  index >= 0        if(index<3){            return  0;        }else if(index==3){            return  1;        }        else return tetranacci1(index-1) + tetranacci1(index-2)+ tetranacci1(index-3) + tetranacci1(index-4);    }    long tetranacci2(int index){        // index start from 0, index >= 0        long[] result = teranacci2Helper(index);        if(index< 4){            return result[index];        }else return result[3];    }    long [] teranacci2Helper(int index){        long[] baseArr = {0,0,0,1};        if (index < 4){            return  baseArr;        }        else{            long[] preArr = teranacci2Helper(index-1);            long s = 0;            for (int i=0;i<4;i++ ){                s+=preArr[i];            }            for(int i=0;i<3;i++){                baseArr[i] = preArr[i+1];            }            baseArr[3] = s;            return baseArr;        }    }    double countTime1(int index){           double t0 = System.currentTimeMillis();           System.out.println("Tetranacci1 ("+index+") = "+tetranacci1(index));           double t1 = System.currentTimeMillis();           return  t1 - t0;    }    double countTime2(int index){        double t0 = System.currentTimeMillis();        System.out.println("Tetranacci2 ("+index+") = "+tetranacci2(index));        double t1 = System.currentTimeMillis();        return t1-t0;    }    public static void main(String [] args){        int num = 8;        double time[][] = new double[num][2];        Assignment1 ass1 = new Assignment1();        for(int i=1;i<=num; i++){            time[i-1][0] = ass1.countTime1(5*i);            time[i-1][1] = ass1.countTime2(5*i);        }        PrintWriter writer;        try {            writer = new PrintWriter("out.txt", "utf-8");            for(int i=0; i<num; i++){                writer.println(time[i][0] + " " + time[i][1]);            }            writer.close();        }catch (Exception e){            e.printStackTrace();        }    }}