then begin
tmp[t]:=a[i]; inc(i);
end
else begin
tmp[t]:=a[j];inc(j);
end;
inc(t);
end;
for i:=p to r do a[i]:=tmp[i];
end;{merge}
procedure merge_sort(var a:listtype; p,r: integer); {合并排序a[p..r]}
var q:integer;
begin
if p<>r then begin
q:=(p+r-1) div 2;
merge_sort (a,p,q);
merge_sort (a,q+1,r);
merge (a,p,q,r);
end;
end;
{main}
begin
merge_sort(a,1,n);
end.
G.基数排序
思想:对每个元素按从低位到高位对每一位进行一次排序
五、高精度计算
高精度数的定义:
type
hp=array[1..maxlen] of integer;
1.高精度加法
procedure plus ( a,b:hp; var c:hp);
var i,len:integer;
begin
fillchar(c,sizeof(c),0);
if a[0]>b[0] then len:=a[0] else len:=b[0];
for i:=1 to len do begin
inc(c[i],a[i]+b[i]);
if c[i]>10 then begin dec(c[i],10); inc(c[i+1]); end; {进位}
end;
if c[len+1]>0 then inc(len);
c[0]:=len;
end;{plus}
2.高精度减法
procedure substract(a,b:hp;var c:hp);
var i,len:integer;
begin
fillchar(c,sizeof(c),0);
if a[0]>b[0] then len:=a[0] else len:=b[0];
for i:=1 to len do begin
inc(c[i],a[i]-b[i]);
if c[i]<0 then begin inc(c[i],10);dec(c[i+1]); end;
while (len>1) and (c[len]=0) do dec(len);
c[0]:=len;
end;
3.高精度乘以低精度
procedure multiply(a:hp;b:longint;var c:hp);
var i,len:integer;
begin
fillchar(c,sizeof(c),0);
len:=a[0];
for i:=1 to len do begin
inc(c[i],a[i]*b);
inc(c[i+1],(a[i]*b) div 10);
c[i]:=c[i] mod 10;
end;
inc(len);
while (c[len]>=10) do begin {处理最高位的进位}
c[len+1]:=c[len] div 10;
c[len]:=c[len] mod 10;
inc(len);
end;
while (len>1) and (c[len]=0) do dec(len); {若不需进位则调整len}
c[0]:=len;
end;{multiply}
4.高精度乘以高精度
procedure high_multiply(a,b:hp; var c:hp}
var i,j,len:integer;
begin
fillchar(c,sizeof(c),0);
for i:=1 to a[0] do
for j:=1 to b[0] do begin
inc(c[i+j-1],a[i]*b[j]);
inc(c[i+j],c[i+j-1] div 10);
c[i+j-1]:=c[i+j-1] mod 10;
end;
len:=a[0]+b[0]+1;
while (len>1) and (c[len]=0) do dec(len);
c[0]:=len;
end;
5.高精度除以低精度
procedure devide(a:hp;b:longint; var c:hp; var d:longint);
{c:=a div b; d:= a mod b}
var i,len:integer;
begin
fillchar(c,sizeof(c),0);
len:=a[0]; d:=0;
for i:=len downto 1 do begin
d:=d*10+a[i];
c[i]:=d div b;
d:=d mod b;
end;
while (len>1) and (c[len]=0) then dec(len);
c[0]:=len;
end;
6.高精度除以高精度
procedure high_devide(a,b:hp; var c,d:hp);
var
i,len:integer;
begin
fillchar(c,sizeof(c),0);
fillchar(d,sizeof(d),0);
len:=a[0];d[0]:=1;
for i:=len downto 1 do begin
multiply(d,10,d);
d[1]:=a[i];
while(compare(d,b)>=0) do {即d>=b}
c算法大全常用c语言算法,包括数论算法,图论算法、排序算法、高精度计算、树的遍历算法等等



