基本算法(用 PASCAL 描述)
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(`;qF6U2_2`~c(R0转:http://www.cnblogs.com/dingjie/archive/2005/07/15/193216.html51Testing软件测试网2jk9V#pj-H&D4~
JN6Oq9X#?S&`ID0基本算法(用 PASCAL 描述)51Testing软件测试网Hw!Q@!W2L!z
1.数论算法
N[ b?0BVYkL)Z0求两数的最大公约数51Testing软件测试网w MippHH_n
function gcd(a,b:integer):integer;
r3dDI}5a8xDSG b0begin
8PU:ip5~7^Q5_cu1F0if b=0 then gcd:=a51Testing软件测试网M bF1|p B/o
else gcd:=gcd (b,a mod B);51Testing软件测试网.eNl2Vs D0F&{8e?
end;
{R*G,pk4gn0
C"[.k o/g$zB%n5n0求两数的最小公倍数
{.u?f@+XT4{0function lcm(a,b:integer):integer;51Testing软件测试网#NlwHU|4]
begin
9xo/};X4t@^0if a< b then swap(a,B);51Testing软件测试网$K q;K'~@!H L+lC/Y
lcm:=a;
;?`]1dr zie'D$p0while lcm mod b >0 do inc(lcm,a);51Testing软件测试网:~7p6x'\`cI'L
end;
I9r(yxf[F^051Testing软件测试网jE#C#\6n3k
素数的求法
.N_v _ @$D$u;T0A.小范围内判断一个数是否为质数:
`7[;u\t%G2Z0function prime (n: integer): Boolean;
l.j(_4Zq["ZM*W0var I: integer;
:LDO!ve^$A0begin51Testing软件测试网\3`6G8Os%`
for I:=2 to trunc(sqrt(n)) do
9CbV mh8\0if n mod I=0 then begin51Testing软件测试网3R5l|6kC&L2w
prime:=false; exit;51Testing软件测试网.?#Q.H Z+\&x
end;
%^?j$rAj)gLz*u H!h0prime:=true;51Testing软件测试网x`ATJ
end;
U?.N.i"|0
j2Dci$ZN;??0ac0B.判断longint范围内的数是否为素数(包含求50000以内的素数表):
0t[z"O+b!}0C|n|0procedure getprime;51Testing软件测试网C8u-mbM"v
var
tfo,H;dtC1eb0i,j:longint;51Testing软件测试网 [ Q&e7e J^(q1al
p:array[1..50000] of boolean;
A3?TY-rSW`~0begin51Testing软件测试网4b\-j1} n }[/n
fillchar(p,sizeof(p),true);
$tDB p Ve\0p[1]:=false;51Testing软件测试网mJ$cLh
i:=2;
~k9~x2}ruch0while i< 50000 do begin51Testing软件测试网#] O3Q` H+X.Z
if p[i] then begin51Testing软件测试网rigC:`6w!t MI
j:=i*2;51Testing软件测试网)f$}+c s-vV
while j< 50000 do begin
Af0qp;A M:S2['A0p[j]:=false;51Testing软件测试网 nBZ"^s O)S.u*s
inc(j,i);51Testing软件测试网X0aE y3j
end;
X]![\$P kFLd.p0end;51Testing软件测试网-IHb#|x-Q`,?U
inc(i);51Testing软件测试网1}iZ!dRS$}0K2Hy
end;51Testing软件测试网7f?d ^C0TF1~s
l:=0;51Testing软件测试网"SL GP K@Z.h
for i:=1 to 50000 do
$i_w/u#bhp%wX|0if p[i] then begin
"n Vo-n1|2H0inc(l);pr[l]:=i;
.{;] zrZ%AeLF#d:D0end;
']-}vz zs0end;{getprime}51Testing软件测试网/GQ#{1[R|Nf"y+f
N[ b?0BVYkL)Z0求两数的最大公约数51Testing软件测试网w MippHH_n
function gcd(a,b:integer):integer;
r3dDI}5a8xDSG b0begin
8PU:ip5~7^Q5_cu1F0if b=0 then gcd:=a51Testing软件测试网M bF1|p B/o
else gcd:=gcd (b,a mod B);51Testing软件测试网.eNl2Vs D0F&{8e?
end;
{R*G,pk4gn0
C"[.k o/g$zB%n5n0求两数的最小公倍数
{.u?f@+XT4{0function lcm(a,b:integer):integer;51Testing软件测试网#NlwHU|4]
begin
9xo/};X4t@^0if a< b then swap(a,B);51Testing软件测试网$K q;K'~@!H L+lC/Y
lcm:=a;
;?`]1dr zie'D$p0while lcm mod b >0 do inc(lcm,a);51Testing软件测试网:~7p6x'\`cI'L
end;
I9r(yxf[F^051Testing软件测试网jE#C#\6n3k
素数的求法
.N_v _ @$D$u;T0A.小范围内判断一个数是否为质数:
`7[;u\t%G2Z0function prime (n: integer): Boolean;
l.j(_4Zq["ZM*W0var I: integer;
:LDO!ve^$A0begin51Testing软件测试网\3`6G8Os%`
for I:=2 to trunc(sqrt(n)) do
9CbV mh8\0if n mod I=0 then begin51Testing软件测试网3R5l|6kC&L2w
prime:=false; exit;51Testing软件测试网.?#Q.H Z+\&x
end;
%^?j$rAj)gLz*u H!h0prime:=true;51Testing软件测试网x`ATJ
end;
U?.N.i"|0
j2Dci$ZN;??0ac0B.判断longint范围内的数是否为素数(包含求50000以内的素数表):
0t[z"O+b!}0C|n|0procedure getprime;51Testing软件测试网C8u-mbM"v
var
tfo,H;dtC1eb0i,j:longint;51Testing软件测试网 [ Q&e7e J^(q1al
p:array[1..50000] of boolean;
A3?TY-rSW`~0begin51Testing软件测试网4b\-j1} n }[/n
fillchar(p,sizeof(p),true);
$tDB p Ve\0p[1]:=false;51Testing软件测试网mJ$cLh
i:=2;
~k9~x2}ruch0while i< 50000 do begin51Testing软件测试网#] O3Q` H+X.Z
if p[i] then begin51Testing软件测试网rigC:`6w!t MI
j:=i*2;51Testing软件测试网)f$}+c s-vV
while j< 50000 do begin
Af0qp;A M:S2['A0p[j]:=false;51Testing软件测试网 nBZ"^s O)S.u*s
inc(j,i);51Testing软件测试网X0aE y3j
end;
X]![\$P kFLd.p0end;51Testing软件测试网-IHb#|x-Q`,?U
inc(i);51Testing软件测试网1}iZ!dRS$}0K2Hy
end;51Testing软件测试网7f?d ^C0TF1~s
l:=0;51Testing软件测试网"SL GP K@Z.h
for i:=1 to 50000 do
$i_w/u#bhp%wX|0if p[i] then begin
"n Vo-n1|2H0inc(l);pr[l]:=i;
.{;] zrZ%AeLF#d:D0end;
']-}vz zs0end;{getprime}51Testing软件测试网/GQ#{1[R|Nf"y+f