查找第k小元素 查找第k小元素即在n个元素中(未排序)找到第k小的元素。方法同快速排序,采用递归方式。 程序如下: program kspv;
const n=7;
type
arr=array[1..n] of integer;
var
b:arr;
i,k:integer;
function p(s,t:integer):integer;
var i,j,t1,x:integer;
begin
i:=s;j:=t;x:=b;
repeat
while (b[j]>=x) and (j>i) do j:=j-1;
if j>i then begin t1:=b; b:=b[j];b[j]:=t1;end;
while (b<=x) and (i<j) do i:=i+1;
if i<j then begin t1:=b[j];b[j]:=b;b:=t1; end
until i=j;
b:=x;
p:=i;
end;
function find(s,t,k:integer):integer;
var p1,q:integer;
begin
if s=t then find:=b else
begin
p1:=p(s,t);
q:=p1-s+1;
if k<=q then find:=find(s,p1,k) else find:=find(p1+1,t,k-q);
end;
end;
begin
write('input data:');
for i:=1 to n do read(b);readln;
write('input k:');read(k);
write('output data:');
writeln('kthsmall:=',find(1,n,k));
end.
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