39 lines
1.2 KiB
Common Lisp
39 lines
1.2 KiB
Common Lisp
;;;; Quick Find Algorithm
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;;;; This algorithm solve dynamic connectivity
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;;;; problem by providing a way to find if there
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;;;; is a path between two nodes in a dynamic graph
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(in-package :com.lisp-algo.union-find)
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(defclass quick-find ()
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((nw-size
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:initarg :network-size
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:initform 10
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:accessor network-size)
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(nw
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:initform nil
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:accessor network)))
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(defmethod initialize-instance :after ((algo quick-find) &key)
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;; Initialize network using dynamic vector
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(let* ((nw-size (slot-value algo 'nw-size))
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(nodes (make-array nw-size :fill-pointer 0)))
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(dotimes (id nw-size)
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(vector-push id nodes))
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(setf (slot-value algo 'nw) nodes)))
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(defmethod union ((algo-instance quick-find) n1 n2)
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(with-slots ((nw nw)) algo-instance
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(let ((v-n1 (elt nw n1))
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(v-n2 (elt nw n2))
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(new-network (copy-seq nw)))
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(dotimes (n (length new-network))
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(if (= (elt new-network n) v-n2) (setf (elt new-network n) v-n1)))
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(setf nw new-network))))
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(defmethod connected ((algo-instance quick-find) n1 n2)
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" Return t if there is a path between n1 and n2, nil otherwise. connected represent the find operation of the Quick Find Algorithm"
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(with-slots ((nw nw)) algo-instance
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(= (elt nw n1) (elt nw n2))))
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