I cant ivent any tests that my solution will fail, but I have WA1!
Can any body help...
Give me some test!
Plz...

example tests
4
0110
0011
0001
1000
4
1 4
2 3
3 2
4 1
my output:
No
No
No
No
3
010
000
100
3
1 3
3 1
2 3
out:
No
Yes
No
Is it correct?
Give some more tests!

You should print "YES", but not "Yes"...

WA 2
CODE:
program china;
var
t:char;
i,j,k:integer;
a:array[1..100,1..100] of boolean;
b:array[1..100] of integer;
chk:array[1..100] of boolean;
x,y,q,n,m:integer;

procedure solve(k:integer);
var
i:integer;
begin
for i:=1 to n do begin
if a[k,i] then begin
if not chk[i] then begin
chk[i]:=true;
solve(i);
end;
end;
end;
end;

begin
readln(n);
for i:=1 to n do begin
for j:=1 to n do begin
read(t);
if t='0' then a[i,j]:=false else a[i,j]:=true;
end;
readln;
end;

for i:=1 to n do begin
fillchar(chk,n,false);
solve(i);
for j:=1 to n do begin
if chk[j] then b[i]:=b[i]+1;
end;
end;

readln(q);
for i:=1 to q do begin
readln(x,y);
if b[x]>b[y] then writeln('YES') else writeln('No');
end;
end.

may be this test will help you:
4
0010
0001
0100
0000
4
1 2
1 4
4 1
4 3

answer:
YES
YES
YES
No

Why answer for 1 4 and 4 1 YES
and what is the anwer for

4
0100
0000
0001
0000
7
1 2
2 1
3 4
4 3
3 1
1 3
3 2

Because you should print "No" only if nodex x and y have common predecessor. In other cases you should print "YES".

My answer for your test:
YES
YES
YES
YES
YES
YES
YES

Thank you, your answer helped me mutch!

Where this is written in the statement? Why can't I solve the problem this way:
1. Make transitive closure of the given graph (matrix A)using Floyd.
2. For every request (pair i j) print "YES" if A[i][j] = 1 otherwise print "No".

Here:
 "In this case we say that the team A is stronger than the teams B and C (more formally, A is stronger than B if A has beaten B or if A has beaten a team C which is stronger than B)."

Edited by author 18.10.2006 23:11

Edited by author 18.10.2006 23:11

4 1 anwer is No, because 1 better than 3, 3 better than 2, 2 better than 4 => 1 better than 4