算法——兔子问题

有一对兔子，从出生后第3个月起每个月都生一对兔子，小兔子长到第3个月后每个月又生一对兔子，假如兔子都不死，问每个月的兔子总数为多少？

package com.test.one;

public class Rabbit {

public static int CountRabbit(int months,int initNum){

int sum=2;

int lastNum=initNum;

int beforeLastNum=initNum;

int eachMonthNum=0;

if(months<=2){

return sum;

}

for(int i=2;i<months;i++){

eachMonthNum=lastNum+beforeLastNum;

sum=sum+eachMonthNum;//this month num

beforeLastNum=lastNum;

lastNum=eachMonthNum;

}

return sum;

}

public static void main(String[] args) {

//1,1,2,3,5,8 (couple)

int sum=0;//total couple

int months=6;//查看第6个月

int initNum=1;//init, 1 couple

sum=CountRabbit(months,initNum);

System.out.println("the total rabbit number is "+sum);

}

}