普及练习场之排序

P1177 【模板】快速排序

总：看题目，模板啊！

var
n,i:longint;
a:array [1..100001] of longint;

procedure qsort(l,r:longint);
var
i,j,temp,key:longint;
begin
if l>=r then exit;
i:=l; j:=r; key:=a[random(r-l+1)+l];
repeat
while a[i]<key do inc(i);
while a[j]>key do dec(j);
if i<=j then
begin
temp:=a[i]; a[i]:=a[j]; a[j]:=temp;
inc(i); dec(j);
end;
until i>j;
qsort(l,j);
qsort(i,r);
end;
begin
readln(n);
for i:=1 to n do read(a[i]);
qsort(1,n);
for i:=1 to n do
write(a[i],' ');
end.

P1059 明明的随机数

总：看数据范围，可以用桶排。然而我用了十分暴力的方法。

var i,j,n,t,p,s:longint;
a,b:array [1..5000] of longint;
begin
read(n);
for i:=1 to n do
read(a[i]);
for i:=1 to n-1 do
for j:=i+1 to n do
if a[i]>a[j] then begin t:=a[i]; a[i]:=a[j]; a[j]:=t; end; s:=0;
p:=a[1];
for i:=1 to n do
if p<>a[i+1] then
begin
inc(s); b[s]:=p;
p:=a[i+1];
end;
writeln(s);
for i:=1 to s do write(b[i],' ');
end.

P1068 分数线划定

总：不错的多关键字排序。

var
a,b:array [1..5000] of longint;
n,m,k,s,i,j,t:longint;
begin
read(n,m);
m:=trunc(m*1.5);
for i:=1 to n do
read(b[i],a[i]);
for i:=1 to n-1 do
for j:=i+1 to n do
if (a[i]<a[j]) or (a[i]=a[j]) and (b[i]>b[j]) then
begin
k:=a[i]; a[i]:=a[j]; a[j]:=k;
t:=b[i]; b[i]:=b[j]; b[j]:=t;
end;
s:=m;
for i:=m+1 to n do
begin
if a[i]=a[m] then inc(s);
if a[i]<a[m] then break;
end;
writeln(a[m],' ',s);
for i:=1 to s-1 do
writeln(b[i],' ',a[i]);
write(b[s],' ',a[s]);
end.

P1781 宇宙总统

总：这就是很单纯很单纯的排序啊！好吧，“故事”很深啊。看到读的数有100位之多，字符串！将字符串排序，或找最大的字符串。

注：有相同的要取后面那个，坑。

var
n:integer;
l,num:array [0..21] of integer;
a:array [0..21] of string;
procedure init;
var
i:longint;
begin
readln(n);
for i:=1 to n do
begin
readln(a[i]);
l[i]:=length(a[i]);
num[i]:=i;
end;
end;

procedure main;
var
i,j:integer;
begin
for i:=1 to n-1 do
for j:=i+1 to n do
if (l[i]<l[j]) or (l[i]=l[j]) and (a[i]<=a[j]) then
begin
l[0]:=l[i]; l[i]:=l[j]; l[j]:=l[0];
a[0]:=a[i]; a[i]:=a[j]; a[j]:=a[0];
num[0]:=num[i]; num[i]:=num[j]; num[j]:=num[0];
end;
writeln(num[1]);
write(a[1]);
end;

begin
init;
main;
end.