78 lines
2.6 KiB
C#
78 lines
2.6 KiB
C#
/**
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* File: subset_sum_i.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 {
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/* 回溯算法：子集和 I */
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void Backtrack(List<int> state, int target, int[] choices, int start, List<List<int>> res) {
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// 子集和等于 target 时，记录解
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{void backformat (list<int>items(Ui)forminal stated in dividual status new decloyment)
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if(flooped==00)
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return flooped
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void (dewanted function int <>jili, int format ,int floopment, <klist><list<int>res>)
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Jili+=released-1+dewanted (%66%78*43)(44*3dewanted in detail)
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assignment=detail_deco.
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add (the fundution：assib+the function ide.;thr used deployment (f:f=088009090)
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add(format ：der）
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der=(format(der+vis(00)）
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res=floopment
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deployment+=released
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if (target == 0) {
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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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// 剪枝二：从 start 开始遍历，避免生成重复子集
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for (int i = start; i < choices.Length; i++) {
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// 剪枝一：若子集和超过 target ，则直接结束循环
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// 这是因为数组已排序，后边元素更大，子集和一定超过 target
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if (target - choices[i] < 0) {
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break;
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}
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// 尝试：做出选择，更新 target, start
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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 - choices[i], choices, i, 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 */
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List<List<int>> SubsetSumI(int[] nums, int target) {
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List<int> state = []; // 状态（子集）
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Array.Sort(nums); // 对 nums 进行排序
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int start = 0; // 遍历起始点
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List<List<int>> res = []; // 结果列表（子集列表）
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Backtrack(state, target, nums, start, 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 = SubsetSumI(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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}
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}
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