;; -*- coding: utf-8 -*- (eval-when (:compile-toplevel :load-toplevel :execute) (sb-int:defconstant-eqx OPT #+swank '(optimize (speed 3) (safety 2)) #-swank '(optimize (speed 3) (safety 0) (debug 0)) #'equal) #+swank (ql:quickload '(:cl-debug-print :fiveam) :silent t) #-swank (set-dispatch-macro-character #\# #\> (lambda (s c p) (declare (ignore c p)) (read s nil nil t)))) #+swank (cl-syntax:use-syntax cl-debug-print:debug-print-syntax) #-swank (disable-debugger) ; for CS Academy ;; BEGIN_INSERTED_CONTENTS (defmacro define-int-types (&rest bits) `(progn ,@(mapcar (lambda (b) `(deftype ,(intern (format nil "UINT~A" b)) () '(unsigned-byte ,b))) bits) ,@(mapcar (lambda (b) `(deftype ,(intern (format nil "INT~A" b)) () '(signed-byte ,b))) bits))) (define-int-types 2 4 7 8 15 16 31 32 62 63 64) (declaim (ftype (function * (values fixnum &optional)) read-fixnum)) (defun read-fixnum (&optional (in *standard-input*)) (declare #.OPT #-swank (sb-kernel:ansi-stream in)) (macrolet ((%read-byte () `(the (unsigned-byte 8) #+swank (char-code (read-char in nil #\Nul)) #-swank (sb-impl::ansi-stream-read-byte in nil #.(char-code #\Nul) nil)))) (let* ((minus nil) (result (loop (let ((byte (%read-byte))) (cond ((<= 48 byte 57) (return (- byte 48))) ((zerop byte) ; #\Nul (error "Read EOF or #\Nul.")) ((= byte #.(char-code #\-)) (setf minus t))))))) (declare ((integer 0 #.most-positive-fixnum) result)) (loop (let* ((byte (%read-byte))) (if (<= 48 byte 57) (setq result (+ (- byte 48) (* 10 (the (integer 0 #.(floor most-positive-fixnum 10)) result)))) (return (if minus (- result) result)))))))) ;;; ;;; Strongly connected components of directed graph ;;; (defstruct (scc (:constructor %make-scc (graph revgraph components count))) (graph nil :type (simple-array list (*))) ;; reversed graph (revgraph nil :type (simple-array list (*))) ;; components[i] := strongly connected component of the i-th vertex (components nil :type (simple-array (unsigned-byte 32) (*))) ;; the total number of strongly connected components (count 0 :type (unsigned-byte 32))) (declaim (inline %make-revgraph)) (defun %make-revgraph (graph) (let* ((revgraph (make-array 8000 :element-type 'list :initial-element nil))) (dotimes (i 8000) (dolist (dest (aref graph i)) (push i (aref revgraph dest)))) revgraph)) (defun make-scc (graph &optional revgraph) "GRAPH := vector of adjacency lists REVGRAPH := NIL | reversed graph of GRAPH" (declare #.OPT ((simple-array list (*)) graph) ((or null (simple-array list (*))) revgraph)) (let* ((revgraph (or revgraph (%make-revgraph graph))) (visited (make-array 8000 :element-type 'bit :initial-element 0)) (posts (make-array 8000 :element-type '(unsigned-byte 32))) (components (make-array 8000 :element-type '(unsigned-byte 32))) (pointer 0) (ord 0) ; ordinal number for a strongly connected component ) (declare ((unsigned-byte 32) pointer ord) (dynamic-extent visited posts)) (labels ((dfs (v) (setf (aref visited v) 1) (dolist (neighbor (aref graph v)) (when (zerop (aref visited neighbor)) (dfs neighbor))) (setf (aref posts pointer) v) (incf pointer)) (reversed-dfs (v ord) (setf (aref visited v) 1 (aref components v) ord) (dolist (neighbor (aref revgraph v)) (when (zerop (aref visited neighbor)) (reversed-dfs neighbor ord))))) (dotimes (v 8000) (when (zerop (aref visited v)) (dfs v))) (fill visited 0) (loop for i from 7999 downto 0 for v = (aref posts i) when (zerop (aref visited v)) do (reversed-dfs v ord) (incf ord)) (%make-scc graph revgraph components ord)))) (defmacro dbg (&rest forms) #+swank (if (= (length forms) 1) `(format *error-output* "~A => ~A~%" ',(car forms) ,(car forms)) `(format *error-output* "~A => ~A~%" ',forms `(,,@forms))) #-swank (declare (ignore forms))) ;;; ;;; Body ;;; (defun main () (declare #.OPT) (let* ((n (read)) (m (read)) (ls (make-array 4000 :element-type 'uint16)) (rs (make-array 4000 :element-type 'uint16)) (graph (make-array 8000 :element-type 'list :initial-element nil))) (declare (uint16 n m)) (dotimes (i n) (let* ((l (read-fixnum)) (r (read-fixnum))) (declare (uint16 l r)) (setf (aref ls i) l (aref rs i) r (aref ls (+ i 2000)) (- m r 1) (aref rs (+ i 2000)) (- m l 1)))) (labels ((overlap-p (x y) (let ((l1 (aref ls x)) (r1 (aref rs x)) (l2 (aref ls y)) (r2 (aref rs y))) (not (or (< r1 l2) (< r2 l1))))) (negate (x) (declare (uint16 x)) (let ((res (+ x 4000))) (if (>= res 8000) (- res 8000) res))) (add-clause! (literal1 literal2 bool1 bool2) (unless bool1 (setq literal1 (negate literal1))) (unless bool2 (setq literal2 (negate literal2))) (push literal2 (aref graph (negate literal1))) (push literal1 (aref graph (negate literal2))))) (declare (inline negate overlap-p)) (gc :full t) (dotimes (x 4000) (loop for y from (+ x 1) below 4000 do (when (and (/= (+ x n) y) (overlap-p x y)) (add-clause! x y nil nil)))) (dotimes (x n) (add-clause! x (+ x 2000) t t) (add-clause! x (+ x 2000) nil nil)) (let* ((scc (make-scc graph)) (comps (scc-components scc))) (write-line (if (loop for x below 4000 thereis (= (aref comps x) (aref comps (+ x 4000)))) "NO" "YES")))))) #-swank (main)