Pagini recente » Cod sursa (job #703702) | Cod sursa (job #1833214) | Cod sursa (job #2203720) | Cod sursa (job #1206810) | Cod sursa (job #640444)
Cod sursa(job #640444)
Program dezastru;
var a:array [0..26,0..26] of double;
b:array [0..26] of double;
n,k,i,j:byte;
fi,fo:text;
function comb(n,k:byte):double;
begin
comb:=1;
for i:=1 to n do begin
comb:=comb*i;
if i<=n-k then comb:=comb/i;
if i<=k then comb:=comb/i;
end;
end;
begin
assign(fi,'dezastru.in');
assign(fo,'dezastru.out');
reset(fi); rewrite(fo);
readln(fi,n,k);
for i:=1 to n do begin read(fi,b[i]); a[i,0]:=1; end;
a[0,0]:=1;
for i:=1 to k do
for j:=i to n do
a[j,i]:=a[j-1,i]+a[j-1,i-1]*b[j];
write(fo,a[n,k]/comb(n,k):0:6);
close(fo);
end.