Could you tell me the algorithm?

my email is : smzyjsj1@mail.wh.ah163.net

    A person knowing elementary physics may think that, if the
dart touches the board, it gets stuck in it.

    Well, the one that wrote this problem failed to consider
this: you'll usually get an equation depeding of t^2. If it has two
positive solutions, you must report "HIT", if for any of them the
dart is inside the board.

    I got stuck with this for 3 days - if I had two positive
solutions, I only checked for the smaller one, and considered the
dart stays there (reality check!!)... well, looks like the dart can
very well get through the board, and then get back in it.

var a:array[1..100,1..100]of longint;
    n,q:longint;
    b:array[1..10000]of longint;
    c:array[1..10000]of longint;
    noch,koch,i,ch1,ch2,s:longint;
    d:array[1..10000]of longint;
function find:longint;
var i:longint;
    max:longint;
begin
 max:=0;
 while noch<=koch do
  begin
   for i:=1 to n do
    if a[b[noch],i]<>0 then
     begin
      inc(koch);
      b[koch]:=i;
      c[koch]:=c[noch]+a[b[noch],i];
      d[koch]:=d[noch]+1;
      a[b[noch],i]:=0;
      a[i,b[noch]]:=0;
      if (d[koch]=q)and(c[koch]>max)then max:=c[koch];
      if d[koch]>q then break;
     end;
   inc(noch);
  end;
 find:=max;
end;
begin
 readln(n,q);
 for i:=1 to n-1 do
  begin
   readln(ch1,ch2,s);
   a[ch1,ch2]:=s;
   a[ch2,ch1]:=s;
  end;
 noch:=1;koch:=1;
 b[koch]:=1;
 writeln(find);
end.

Compilation Error  PROBLEM3 1021
program ViniT;
var
a,b:array[1..10000]of integer;
u,i,j,n,k:integer;
o:boolean;
procedure swap(var a,b:integer);
var t:integer;
begin
t:=a;
a:=b;
b:=t;
end;
procedure qsort(m,l:integer);
var
i,j,k:integer;
begin
k:=a[(m+l)div 2];
i:=m;j:=l;
repeat
    while a[i]<k do inc(i);
    while a[j]>k do dec(j);
    if i<=j then begin  swap(a[i],a[j]);dec(j);inc(i);end;
until i>j;
if m<j then  qsort(m,j);
if l>i then qsort(i,l);
end;

procedure init;
begin
read(n);
for i:=1 to n do read(a[i]);
read(k);
for i:=1 to k do read(b[i]);
qsort(1,n);
end;

function find(m,l:integer):boolean;
var k:integer;
begin
if m=l then find:=u+a[m]=10000 else begin
   k:=(m+l)div 2;
   if u+a[k]<10000 then find:=find(k+1,l)
   else if u+a[k]>10000 then find:=find(m,k-1)
   else find:=true;
end;
end;
procedure solve;
begin
o:=false;
for i:=1 to k do begin
    u:=b[i];
    o:=find(1,n);
    if o then i:=k;
end;
end;
procedure print;
begin
if o then write('YES')else write('NO');
end;
begin
init;
solve;
print;
end.

program ex;
const
  max=100;
var
  j,st,z,ch,n,i:integer;
  gh:array[1..max,1..max]of boolean;
  flag:boolean;
  ans:array[1..max]of integer;
begin
  z:=1;
  fillchar(gh,sizeof(gh),false);
{  assign(input,'d:\input.txt');
  reset(input);}
  readln(n);
  for i:=1 to n do
  begin
     read(ch);
     if ch=0 then begin writeln(0); halt; end;
     while ch<>0 do
     begin
       gh[i,ch]:=true;
       gh[ch,i]:=true;
       read(ch);
     end;
     readln;
  end;
{ close(input);}
  st:=1;
  ans[z]:=st;
  flag:=true;
  while st<n do
  begin
    j:=st+1;
    while gh[st,j]=true do j:=j+1;
    if j>n then break;
    z:=z+1;
    ans[z]:=j;
    st:=j;
  end;
  writeln(z);
  for i:=1 to z do write(ans[i],' ');
  writeln;
end.

What happened with this ID's submissions and the problem 1188 :-/

#include <iostream.h>
#include <math.h>
void main()
{   float k;
    long i,l;
cin>>k;
{l=int(k)-1;
for(i=2;i<=sqrt(k)+4;i++) if ((k/i==int(k/i))&& (i>=3) ){l=i-
1;break;};
cout<<l;};
}
always get wrong answer

program find_a_multiple;

const maxn=1000;

var n:integer;
    a:array[1..maxn] of integer;
    s:array[0..maxn] of integer;
    c:array[1..maxn,0..2] of integer;

procedure init;
  var i:integer;
  begin
    readln(n);
    for i:=1 to n do readln(a[i]);
  end;

procedure out(i,j:integer);
  var k:integer;
  begin
    for k:=i to j do write(a[k],' ');
    writeln;
    halt;
  end;

procedure work;
  var i:integer;
  begin
    fillchar(s,sizeof(s),0);
    for i:=1 to n do s[i]:=(s[i-1]+a[i]) mod n ;

    fillchar(c,sizeof(c),0);
    for i:=1 to n do
      if s[i]=0 then out(1,i)
                else begin
                       inc(c[s[i],0]); c[s[i], c[s[i],0]]:=i;
                       if c[s[i],0]=2 then out(c[s[i],1]+1, c[s
[i],2]);
                     end;
  end;

begin
  init;
  work;
end.

var
  a:array[1..100,0..100] of 0..1;
  b:array[1..100] of integer;
  n,i,j,k:integer;
begin
  readln(n);
  for i:=1 to n do begin
    read(j);
    while j<>0 do begin
      a[i,j]:=1;
      read(j);
    end;
    readln;
    b[i]:=i;
  end;
  for i:=1 to n do
    for j:=1 to n do
      for k:=1 to n do
        if (a[i,j]=1)and(a[j,k]=1) then a[i,k]:=1;
  for i:=1 to n do
    for j:=1 to n do inc(a[i,0],a[i,j]);
  for i:=1 to n-1 do for j:=i+1 to n do
    if a[b[i],0]<a[b[j],0] then begin
      k:=b[i];
      b[i]:=b[j];
      b[j]:=k;
    end;
  for i:=1 to n do write(b[i],' ');
  writeln;
end.

#include <stdio.h>
#include <math.h>

int main()
{
    float ans,r,x[100], y[100];
    int n,i;
    scanf("%d %f", &n, &r);
    for (i = 0; i < n; i++)
    scanf("%f %f", &x[i], &y [i]);
    ans = 2*r*3.14159;
    if (n > 1)
    {
    for (i = 0; i < n-1; i++)
    ans += sqrt( (x[i]-x[i+1])*(x[i]-x[i+1]) + (y[i]-y[i+1]) * (y
[i]-y[i+1]));
    ans += sqrt( (x[n]-x[1])*(x[n]-x[1]) + (y[n]-y[1]) * (y[n]-y
[1]));
    }
    printf("%.2f\n", ans);
    return 0;
}

vladimir_mnog@mail.ru
tnxx

program timus_1028;
const
  maxn=15000;
type
  tcoord=record x,y:integer end;

function Greater(c1,c2:tcoord):boolean;
begin
  Greater:=(c1.x+c1.y)>(c2.x+c2.y);
end;

type
  ta=array[1..maxn]of tcoord;
  tv=array[0..maxn]of word;
var
  n:integer;
  a:ta;
  v:tv;

procedure read_data;
var
  i:integer;
begin
  readln(n);
  for i:=1 to n do
    readln(a[i].x,a[i].y);
end;

procedure Switch(var a,b:tcoord);
var
  c:tcoord;
begin
  c:=a;
  a:=b;
  b:=c;
end;

procedure quicky(start,stop:integer);
var
 ini,fin:integer;
 step:integer;
begin
  if start>=stop then
    exit;
  ini:=start; fin:=stop; step:=1;
  while ini<fin do
  begin
    if Greater(a[ini],a[fin]) then
    begin
      Switch(a[ini],a[fin]);
      step:=1-step;
    end;
    inc(ini,step); dec(fin,1-step);
  end;
  quicky(start,ini-1);
  quicky(fin+1,stop);
end;

procedure sort_data;
begin
  quicky(1,n);
end;

procedure init_data;
begin
  fillchar(v,sizeof(v),0);
end;

procedure make_data;
var
  i:integer;
  k:integer;
begin
  v[0]:=1;k:=0;
  for i:=2 to n do
  begin
    if Greater(a[i],a[i-1]) then
      inc(k);
    inc(v[k]);
  end;
end;

procedure writ_data;
var
  i:integer;
begin
  for i:=0 to n-1 do
    writeln(v[i]);
end;

begin
  read_data;
  sort_data;
  init_data;
  make_data;
  writ_data;
end.

We can know all where we made mistakes.

const MAXN  =  10000;
var N,M,i,j,min:integer;
    K:array[1..100]of integer;
    a:array[1..MAXN]of byte;
begin
  readln(N,M);
  for i:=1 to M do
  begin
     read(K[i]);
  end;
  for i:=1 to N do a[i]:=2;
  min:=MaxInt;
  for i:=1 to M do if min >  k[i] then min:=k[i];
  a[min]:=0;
  for i:=min+1 to N do
  begin
    for j:=1 to M do if (i-K[j]>0)and(a[i-K[j]]<>2) then
    begin
      if a[i-K[j]] = 0 then
      begin
         a[i]:=1;
         break;
      end else a[i]:=0;
    end;
  end;
  if a[N] = 0 then writeln(2)
  else writeln(1);
end.

#include <fstream.h>
#include <math.h>
#include <stdio.h>

 struct point
  {
   double x,y;
  };

 point a[1024],convex[1024],pom;

 double det (double x1,double y1,double x2,double y2,double x3,double
y3)
  {
   return x1*(y2-y3)-y1*(x2-x3)+x2*y3-y2*x3;
  }

 void qsort (long l,long r)
  {
   point z;
   long i,j;
   i=l;
   j=r;
   z=a[(i+j)/2];
   do
    {
     while (det(a[1].x,a[1].y,a[i].x,a[i].y,z.x,z.y)>0.0) i++;
     while (det(a[1].x,a[1].y,a[j].x,a[j].y,z.x,z.y)<0.0) j--;
     if (i<=j)
      {
       pom=a[i];
       a[i]=a[j];
       a[j]=pom;
       i++;
       j--;
      }
    }
   while (i<=j);
   if (l<j) qsort(l,j);
   if (i<r) qsort(i,r);
  }

 void main ()
  {
   long n,i,p,k;
   double d,l;
   cin >> n >> l;
   for (i=1;i<=n;i++)
    cin >> a[i].x >> a[i].y;
//------------------
   p=1;
   for (i=2;i<=n;i++)
    if (a[p].y>a[i].y || (a[p].y==a[i].y && a[p].x>a[i].x))
     p=i;
   pom=a[p];
   a[p]=a[1];
   a[1]=pom;
   qsort(2,n);
   a[n+1]=a[1];
   p=1;
   for (i=2;i<=n;i++)
    if (a[i].y==a[1].y && a[i].x>a[p].x)
     p=i;
   if (p==1)
    p=2;
   convex[1]=a[1];
   convex[2]=a[p];
   k=2;
   for (i=p+1;i<=n+1;i++)
    if (a[i].y>a[1].y || i==n+1)
     {
      convex[++k]=a[i];
      while (det(convex[k-2].x,convex[k-2].y,convex[k-1].x,convex[k-
1].y,convex[k].x,convex[k].y)<=0 && k>2)
       convex[--k]=convex[k+1];
     }
//------------------
   double pi;
   pi=3.14159265358979;
   d=0;
   for (i=1;i<k;i++)
    d+=sqrt((convex[i].x-convex[i+1].x)*(convex[i].x-convex[i+1].x)+
(convex[i].y-convex[i+1].y)*(convex[i].y-convex[i+1].y));
   d+=2*pi*l;
//------------------
   printf("%.0f \n",d);
  }

{$N+,s-}
Program Lucky_ticket;

Type xm=array[-50..200] of integer;
     Lion=array[0..1,-50..1000] of ^xm;

Var k,i,j,m,n,u,v,t,t1:Longint;
    q:double;
    a:Lion;
    LL:array[0..1,-100..1000] of integer;
    c:array[-100..1000] of longint;

Procedure Go(x,y:longint);
var i,j,k,L:longint;
begin
  if LL[t,x]>LL[t1,y] then L:=LL[t,x]
  else L:=LL[t1,y];
  for i:=1 to L do
  begin
    inc(a[t,x]^[i],a[t1,y]^[i]);
    if a[t,x]^[i]>9 then
    begin
      dec(a[t,x]^[i],10);
      inc(a[t,x]^[i+1]);
    end;
  end;
  if a[t,x]^[L+1]<>0 then LL[t,x]:=L+1
  else LL[t,x]:=L;
end;

Procedure Cheng(x:integer);
var i,L:longint;
begin
  fillchar(c,sizeof(c),0);
  for i:=1 to LL[t,x] do
  for j:=1 to LL[t,x] do
  inc(c[i+j-1],a[t,x]^[i]*a[t,x]^[j]);
  for i:=1 to LL[t,x]+LL[t,x] do
  begin
    inc(c[i+1],c[i] div 10);
    c[i]:=c[i] mod 10;
  end;
  if c[LL[t,x]+LL[t,x]]<>0 then L:=LL[t,x]+LL[t,x]
  else L:=LL[t,x]+LL[t,x]-1;
  for i:=L downto 1 do
  write(c[i]);
  writeln;
end;

Begin
  read(n);
  read(m);
  if (m>2*n*9)or(odd(m)) then
  begin
    writeln(0);
    exit;
  end;
  m:=m shr 1;
  for j:=0 to 1 do
  for i:=0 to m+1 do
  begin
    new(a[j,i]);
    fillchar(a[j,i]^,sizeof(a[j,i]^),0);
  end;
  for i:=0 to 9 do
  begin
    a[1,i]^[1]:=1;
    LL[1,i]:=1;
  end;
  t:=1;
  t1:=0;
  for i:=2 to n do
  begin
    t1:=t;
    t:=1-t;
    for j:=0 to m+1 do
    fillchar(a[t,j]^,sizeof(a[t,j]^),0);
    fillchar(LL[t],sizeof(LL[t]),0);
    u:=i*9;
    if m<u then u:=m;
    for j:=0 to u do
    begin
      v:=j-9;
      if v<0 then v:=0;
      for k:=v to j do
      go(j,k);
    end;
    LL[t1]:=LL[t];
  end;
  cheng(m);
End.

Hi!
When reading string from the standart input character by character,
how can I stop reading it and go to the next line of the input..
I mean, when I understand the answer is "NO", I don't need to read
the whole string, as the answer will be the same, I just want to go
to the next line and proceed with the next string.
How to do This?
Thanks in advice :)

I am so stupid . I can't find the way of doing this problem
in O(n*Log(n)) , Can anyone tell me the method ? Thanks a lot !

Do you have the same problem ???

This porblem has not correct test's again.For example, if always
output something like printf("700000\n"); you'll get accepted.