NOIP2016全国信息学分区联赛提高组第二试 组合问题

var
sum,f:array [0..2000,0..2000] of longint;
x,y:array [0..20000] of longint;
i,j,n,m,k,t:longint;
function min(x,y:longint):longint;
begin
if x<y then exit(x)
else exit(y);
end;

function max(x,y:longint):longint;
begin
if x>y then exit(x)
else exit(y);
end;

begin
readln(t,k);
for i:=1 to t do
begin
read(x[i],y[i]);
n:=max(n,x[i]);
m:=max(m,y[i]);
end;
f[1,0]:=1; f[1,1]:=1;
for i:=2 to n do
begin
f[i,0]:=1;
for j:=1 to m do
begin
f[i,j]:=(f[i-1,j]+f[i-1,j-1]) mod k;
if (f[i,j]=0) and (j<=i) then sum[i,j]:=1;
sum[i,j]:=sum[i-1,j]+sum[i,j]+sum[i,j-1]-sum[i-1,j-1];
end;
end;
for i:=1 to t do
writeln(sum[x[i],y[i]]);
end.