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dp/page_replacement: update FIFO to PersistentQueue and LRU to index map #49

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Merged
m-hu merged 1 commit into from
Nov 4, 2026
Merged

dp/page_replacement: update FIFO to PersistentQueue and LRU to index map #49

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58 changes: 33 additions & 25 deletions src/dp/page_replacement/page_replacement.clj
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Original file line number Diff line number Diff line change
@@ -1,8 +1,9 @@
;; page-replacement: FIFO, LRU and randomized marking
;;
;; Simulates FIFO and LRU plus the randomized marking algorithm with
;; a fixed-seed LCG so the eviction choices are deterministic. Emits
;; the three fault counts.
;; Simulates FIFO (PersistentQueue, O(1) amortized ops), LRU
;; (timestamp-indexed map + sorted-set, O(log f) ops), and the
;; randomized marking algorithm with a fixed-seed LCG so the eviction
;; choices are deterministic. Emits the three fault counts.
;; Reads stdin tokens, writes the answer to stdout.

(def digit-values
Expand Down Expand Up @@ -76,31 +77,38 @@
rq (mapv #(nth nums (+ 2 %)) (range m))
rng (atom 42)
rnd (fn [] (swap! rng (fn [x] (mod (+ (* 1103515245 x) 12345) (bit-shift-left 1 31)))) @rng)]
(let [ff (loop [rs rq q [] s #{} acc 0]
(if (empty? rs) acc
(let [p (first rs)]
(cond (<= f 0) (recur (rest rs) q s (inc acc))
(contains? s p) (recur (rest rs) q s acc)
:else (let [[q2 s2] (if (>= (count q) f) [(vec (rest q)) (disj s (first q))] [q s])]
(recur (rest rs) (conj q2 p) (conj s2 p) (inc acc)))))))
lru-res (loop [rs rq lru [] acc 0]
(if (empty? rs) acc
(let [p (first rs)]
(cond (<= f 0) (recur (rest rs) lru (inc acc))
(boolean (some #(= % p) lru))
(recur (rest rs) (conj (vec (remove #(= % p) lru)) p) acc)
:else (let [lru2 (if (>= (count lru) f) (vec (rest lru)) lru)]
(recur (rest rs) (conj lru2 p) (inc acc)))))))
mf (loop [rs rq cache #{} marked #{} acc 0]
(if (empty? rs) acc
(let [p (first rs)]
(cond (<= f 0) (recur (rest rs) cache marked (inc acc))
(contains? cache p) (recur (rest rs) cache (conj marked p) acc)
(< (count cache) f) (recur (rest rs) (conj cache p) (conj marked p) (inc acc))
(let [ff (loop [i 0 q clojure.lang.PersistentQueue/EMPTY s #{} acc 0]
(if (>= i m) acc
(let [p (nth rq i)]
(cond (<= f 0) (recur (inc i) q s (inc acc))
(contains? s p) (recur (inc i) q s acc)
:else (let [[q2 s2] (if (>= (count q) f)
[(pop q) (disj s (peek q))]
[q s])]
(recur (inc i) (conj q2 p) (conj s2 p) (inc acc)))))))
lru-res (loop [i 0 p->t {} t-set (sorted-set) acc 0]
(if (>= i m) acc
(let [p (nth rq i)]
(cond (<= f 0) (recur (inc i) p->t t-set (inc acc))
(contains? p->t p)
(let [old-t (get p->t p)]
(recur (inc i) (assoc p->t p i) (-> t-set (disj [old-t p]) (conj [i p])) acc))
:else
(let [[p->t2 t-set2] (if (>= (count p->t) f)
(let [[ev-t ev-p] (first t-set)]
[(dissoc p->t ev-p) (disj t-set [ev-t ev-p])])
[p->t t-set])]
(recur (inc i) (assoc p->t2 p i) (conj t-set2 [i p]) (inc acc)))))))
mf (loop [i 0 cache #{} marked #{} acc 0]
(if (>= i m) acc
(let [p (nth rq i)]
(cond (<= f 0) (recur (inc i) cache marked (inc acc))
(contains? cache p) (recur (inc i) cache (conj marked p) acc)
(< (count cache) f) (recur (inc i) (conj cache p) (conj marked p) (inc acc))
:else (let [mk (if (>= (count marked) (count cache)) #{} marked)
cands (vec (sort (remove #(contains? mk %) cache)))
ev (nth cands (mod (rnd) (count cands)))]
(recur (rest rs) (conj (disj cache ev) p) (conj (disj mk ev) p) (inc acc)))))))]
(recur (inc i) (conj (disj cache ev) p) (conj (disj mk ev) p) (inc acc)))))))]
(println ff)
(println lru-res)
(println mf)))))
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