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/**
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* File: subset_sum_i_naive.cs
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* Created Time: 2023-06-25
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* Author: hpstory (hpstory1024@163.com)
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*/
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namespace hello_algo.chapter_backtracking;
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public class subset_sum_i_naive {
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/* 回溯算法：子集和 I */
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public static void backtrack(List<int> state, int target, int total, int[] choices, List<List<int>> res) {
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// 子集和等于 target 时，记录解
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if (total == target) {
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res.Add(new List<int>(state));
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return;
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}
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// 遍历所有选择
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for (int i = 0; i < choices.Length; i++) {
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// 剪枝：若子集和超过 target ，则跳过该选择
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if (total + choices[i] > target) {
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continue;
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}
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// 尝试：做出选择，更新元素和 total
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state.Add(choices[i]);
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// 进行下一轮选择
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backtrack(state, target, total + choices[i], choices, res);
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// 回退：撤销选择，恢复到之前的状态
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state.RemoveAt(state.Count - 1);
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}
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}
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/* 求解子集和 I（包含重复子集） */
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public static List<List<int>> subsetSumINaive(int[] nums, int target) {
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List<int> state = new List<int>(); // 状态（子集）
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int total = 0; // 子集和
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List<List<int>> res = new List<List<int>>(); // 结果列表（子集列表）
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backtrack(state, target, total, nums, res);
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return res;
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}
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[Test]
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public void Test() {
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int[] nums = { 3, 4, 5 };
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int target = 9;
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List<List<int>> res = subsetSumINaive(nums, target);
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Console.WriteLine("输入数组 nums = " + string.Join(", ", nums) + ", target = " + target);
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Console.WriteLine("所有和等于 " + target + " 的子集 res = ");
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foreach (var subset in res) {
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PrintUtil.PrintList(subset);
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}
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Console.WriteLine("请注意，该方法输出的结果包含重复集合");
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}
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}
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