2008递推算法递归算法.ppt

文档介绍：递推算法递推算法是一种若干步、重复的简单运算(规律)解决问题的算法。已知—>未知例1ABCDE植树。问A植几棵树,比B多2棵。问B植几棵树,比C多2棵。……E说植了10棵树。求A植几棵?已知条件:a5=10递推式(规律):a4=a5+2vara:array[1..5]oflongint;i:longint;begina[5]:=10;fori:=4downto1doa[i]:=a[i+1]+2;writeln(a[1]);-......varn,a,b,c,i:longint;begina:=0;b:=1;read(n);fori:=3tondobeginc:=a+b;a:=b;b:=c;end;ifn=2thenwriteln(1)elsewriteln(c);,today:longint;begintoday:=1;fori:=10downto2dotoday:=(today+1)*2;writeln(today);(i)varn,i,a,b,c:longint;beginreadln(n);a:=1;b:=2;fori:=3tondobeginc:=a+b;a:=b;b:=c;end;writeln(c);=连续奇数和vari,j,n,a:longint;beginreadln(n);a:=-1;fori:=1ton-1doforj:=1toidoa:=a+2;fori:=1tondobegina:=a+2;write(a,'');end;。varn,i,lx,nx,px,now:longint;beginpx:=0;lx:=1;now:=0;readln(n);fori:=1tondobeginnx:=px+lx;now:=now+nx;px:=lx;lx:=nx;end;ifn=1thenwriteln(2)elsewriteln(now*2);:函数/过程体中出现对自己的调用,称作递归。未知—>已知—>未知例7ABCDE植树。问A植几棵树,比B多2棵。问B植几棵树,比C多2棵……E说植了10棵树。求A植几棵?算法分析:END条件:a5=10递归式(规律):an=an+1+2函数:varn:longint;functiontree(n:longint):longint;beginifn=5thentree:=10elsetree:=tree(n+1)+2;end;BEGINread(n);writeln(tree(n));END.