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Yudong Jin
3f4220de81
* preorder, inorder, postorder -> pre-order, in-order, post-order * Bug fixes * Bug fixes * Update what_is_dsa.md * Sync zh and zh-hant versions * Sync zh and zh-hant versions. * Update performance_evaluation.md and time_complexity.md * Add @khoaxuantu to the landing page. * Sync zh and zh-hant versions * Add @ khoaxuantu to the landing page of zh-hant and en versions.
64 lines
1.5 KiB
Ruby
64 lines
1.5 KiB
Ruby
=begin
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File: coin_change_ii.rb
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Created Time: 2024-05-29
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Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
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=end
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### 零錢兌換 II：動態規劃 ###
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def coin_change_ii_dp(coins, amt)
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n = coins.length
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# 初始化 dp 表
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dp = Array.new(n + 1) { Array.new(amt + 1, 0) }
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# 初始化首列
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(0...(n + 1)).each { |i| dp[i][0] = 1 }
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# 狀態轉移
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for i in 1...(n + 1)
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for a in 1...(amt + 1)
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if coins[i - 1] > a
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# 若超過目標金額，則不選硬幣 i
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dp[i][a] = dp[i - 1][a]
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else
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# 不選和選硬幣 i 這兩種方案之和
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dp[i][a] = dp[i - 1][a] + dp[i][a - coins[i - 1]]
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end
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end
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end
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dp[n][amt]
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end
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### 零錢兌換 II：空間最佳化後的動態規劃 ###
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def coin_change_ii_dp_comp(coins, amt)
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n = coins.length
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# 初始化 dp 表
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dp = Array.new(amt + 1, 0)
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dp[0] = 1
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# 狀態轉移
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for i in 1...(n + 1)
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# 正序走訪
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for a in 1...(amt + 1)
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if coins[i - 1] > a
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# 若超過目標金額，則不選硬幣 i
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dp[a] = dp[a]
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else
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# 不選和選硬幣 i 這兩種方案之和
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dp[a] = dp[a] + dp[a - coins[i - 1]]
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end
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end
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end
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dp[amt]
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end
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### Driver Code ###
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if __FILE__ == $0
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coins = [1, 2, 5]
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amt = 5
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# 動態規劃
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res = coin_change_ii_dp(coins, amt)
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puts "湊出目標金額的硬幣組合數量為 #{res}"
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# 空間最佳化後的動態規劃
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res = coin_change_ii_dp_comp(coins, amt)
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puts "湊出目標金額的硬幣組合數量為 #{res}"
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end
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