From 2f674dc80f0382f1c3178f435714960734dc9d3c Mon Sep 17 00:00:00 2001
From: Nguyễn Gia Phong <mcsinyx@disroot.org>
Date: Sat, 6 Jun 2020 21:33:13 +0700
Subject: Reorganize stuff from secondary school

---
 2ndary/12/TP-HN-2008/R2/tbc.pas | 69 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 2ndary/12/TP-HN-2008/R2/tbc.pas

(limited to '2ndary/12/TP-HN-2008/R2/tbc.pas')

diff --git a/2ndary/12/TP-HN-2008/R2/tbc.pas b/2ndary/12/TP-HN-2008/R2/tbc.pas
new file mode 100644
index 0000000..1a26a91
--- /dev/null
+++ b/2ndary/12/TP-HN-2008/R2/tbc.pas
@@ -0,0 +1,69 @@
+var
+  f : text;
+  i, l, m, n : integer;
+  a : array[1..1000] of longint;
+
+procedure qsort(l, h : integer);
+  var
+    i, j : integer;
+    x, tmp : longint;
+  begin
+    i := l;
+    j := h;
+    x := a[(i + j) div 2];
+    repeat
+      while a[i] < x do inc(i);
+      while x < a[j] do dec(j);
+      if i <= j then
+        begin
+          tmp := a[i];
+          a[i] := a[j];
+          a[j] := tmp;
+          inc(i);
+          dec(j)
+        end
+    until i > j;
+    if l < j then qsort(l, j);
+    if i < h then qsort(i, h)
+  end;
+
+function biin(n0 : integer) : boolean;
+  var l, h, m : integer;
+  begin
+    l := 1;
+    h := n;
+    repeat
+      m := (l + h) div 2;
+      if a[m] = n0 then exit(true);
+      if a[m] < n0 then l := m + 1
+      else h := m - 1
+    until l > h;
+    biin := false
+  end;
+
+function libtbc(n0 : integer) : boolean;
+  var i, j : integer;
+  begin
+    for i := 1 to n0 - 1 do
+      for j := n0 + 1 to n do
+        if biin(a[n0] * 3 - a[i] - a[j]) then
+          exit(true);
+    libtbc := false
+  end;
+
+begin
+  assign(f, 'TBC.INP');
+  reset(f);
+  readln(f, n);
+  for i := 1 to n do readln(f, a[i]);
+  close(f);
+  qsort(1, n);
+  m := 0;
+  for l := 2 to n - 1 do
+    if libtbc(l) then
+      inc(m);
+  assign(f, 'TBC.OUT');
+  rewrite(f);
+  writeln(f, m);
+  close(f)
+end.
-- 
cgit 1.4.1