关于兔子的计划生育

 

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1对兔子,第20个月后共有多少对兔子?

 

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╔═[■]═══════════════════════════════ TZ.PAS ═════════════════════════════1═[↕]═╗
║program lx353;                                                                ▲
║const                                                                         ■
║n=20;                                                                         ▒
║var a0,a1,a2,i:integer;                                                       ▒
║begin                                                                         ▒
║a0:=0;                                                                        ▒
║a1:=1;                                                                        ▒
║for i:=2 to n do                                                              ▒
║  begin                                                                       ▒
║  a2:=a0+a1;                                                                  ▒
║   writeln(i,'   ',a0,'  ',a1,'  ',a2);                                       ▒
║    a0:=a1;                                                                   ▒
║    a1:=a2;                                                                   ▒
║                                                                              ▒
║    end;                                                                      ▒
║                                                                              ▒
║end.                                                                          ▒
║                                                                              ▒
║                                                                              ▒
║                                                                              ▒
║                                                                              ▼

 

我是这样理解的:设置3个变量 a0刚出生的兔子(即要过2个月才能生的兔子)

a1(具有生育能力的兔子)

 a2(兔子总数)

关系a2:=a0+a1;

运行结果

Turbo Pascal  Version 7.0  Copyright (c) 1983,92 Borland International

月份a0a1 a2
2   0  1  1
3   1  1  2
4   1  2  3
5   2  3  5
6   3  5  8
7   5  8  13
8   8  13  21
9   13  21  34
10   21  34  55
11   34  55  89
12   55  89  144
13   89  144  233
14   144  233  377
15   233  377  610
16   377  610  987
17   610  987  1597
18   987  1597  2584
19   1597  2584  4181
20   2584  4181  6765

 

不知道是否有递归的感觉