64 lines
2.0 KiB
Swift
64 lines
2.0 KiB
Swift
/**
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* File: unbounded_knapsack.swift
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* Created Time: 2023-07-15
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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/* Complete knapsack: Dynamic programming */
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func unboundedKnapsackDP(wgt: [Int], val: [Int], cap: Int) -> Int {
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let n = wgt.count
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// Initialize dp table
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var dp = Array(repeating: Array(repeating: 0, count: cap + 1), count: n + 1)
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// State transition
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for i in 1 ... n {
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for c in 1 ... cap {
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if wgt[i - 1] > c {
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// If exceeding the knapsack capacity, do not choose item i
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dp[i][c] = dp[i - 1][c]
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} else {
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// The greater value between not choosing and choosing item i
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dp[i][c] = max(dp[i - 1][c], dp[i][c - wgt[i - 1]] + val[i - 1])
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}
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}
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}
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return dp[n][cap]
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}
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/* Complete knapsack: Space-optimized dynamic programming */
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func unboundedKnapsackDPComp(wgt: [Int], val: [Int], cap: Int) -> Int {
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let n = wgt.count
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// Initialize dp table
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var dp = Array(repeating: 0, count: cap + 1)
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// State transition
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for i in 1 ... n {
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for c in 1 ... cap {
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if wgt[i - 1] > c {
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// If exceeding the knapsack capacity, do not choose item i
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dp[c] = dp[c]
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} else {
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// The greater value between not choosing and choosing item i
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dp[c] = max(dp[c], dp[c - wgt[i - 1]] + val[i - 1])
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}
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}
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}
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return dp[cap]
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}
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@main
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enum UnboundedKnapsack {
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/* Driver Code */
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static func main() {
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let wgt = [1, 2, 3]
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let val = [5, 11, 15]
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let cap = 4
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// Dynamic programming
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var res = unboundedKnapsackDP(wgt: wgt, val: val, cap: cap)
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print("Maximum value of items within the backpack capacity = \(res)")
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// Space-optimized dynamic programming
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res = unboundedKnapsackDPComp(wgt: wgt, val: val, cap: cap)
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print("Maximum value of items within the backpack capacity = \(res)")
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}
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}
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