52 lines
1.6 KiB
Swift
52 lines
1.6 KiB
Swift
/**
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* File: subset_sum_i_naive.swift
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* Created Time: 2023-07-02
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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/* 回溯演算法：子集和 I */
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func backtrack(state: inout [Int], target: Int, total: Int, choices: [Int], res: inout [[Int]]) {
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// 子集和等於 target 時，記錄解
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if total == target {
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res.append(state)
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return
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}
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// 走訪所有選擇
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for i in choices.indices {
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// 剪枝：若子集和超過 target ，則跳過該選擇
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if total + choices[i] > target {
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continue
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}
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// 嘗試：做出選擇，更新元素和 total
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state.append(choices[i])
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// 進行下一輪選擇
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backtrack(state: &state, target: target, total: total + choices[i], choices: choices, res: &res)
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// 回退：撤銷選擇，恢復到之前的狀態
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state.removeLast()
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}
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}
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/* 求解子集和 I（包含重複子集） */
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func subsetSumINaive(nums: [Int], target: Int) -> [[Int]] {
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var state: [Int] = [] // 狀態（子集）
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let total = 0 // 子集和
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var res: [[Int]] = [] // 結果串列（子集串列）
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backtrack(state: &state, target: target, total: total, choices: nums, res: &res)
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return res
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}
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@main
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enum SubsetSumINaive {
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/* Driver Code */
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static func main() {
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let nums = [3, 4, 5]
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let target = 9
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let res = subsetSumINaive(nums: nums, target: target)
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print("輸入陣列 nums = \(nums), target = \(target)")
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print("所有和等於 \(target) 的子集 res = \(res)")
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print("請注意，該方法輸出的結果包含重複集合")
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}
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}
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