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14 lines
387 B
Plaintext
14 lines
387 B
Plaintext
(defn sum3
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"Solve the 3SUM problem in O(n^2) time."
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[s]
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(def tab @{})
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(def solutions @{})
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(def len (length s))
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(loop [k :range [0 len]]
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(put tab (get s k) k))
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(loop [i :range [0 len], j :range [0 len]]
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(def k (get tab (- 0 (get s i) (get s j))))
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(when (and k (not= k i) (not= k j) (not= i j))
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(put solutions {i true j true k true} true)))
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(map keys (keys solution)))
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