71 lines
2.2 KiB
Java
71 lines
2.2 KiB
Java
/*
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* The MIT License (MIT)
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*
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* Copyright © 2022 xrv <xrv@live.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package io.github.ehlxr.algorithm;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* 全排列
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*
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* @author ehlxr
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* @since 2022-04-20 16:42.
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*/
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public class Permutation {
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static List<List<Integer>> res = new ArrayList<>();
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public static void main(String[] args) {
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int[] arr = {1, 2, 3};
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for (List<Integer> r : permute(arr)) {
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for (int i : r) {
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System.out.print(i + " ");
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}
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System.out.println();
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}
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}
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public static List<List<Integer>> permute(int[] nums) {
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List<Integer> track = new ArrayList<>();
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backtrack(nums, track);
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return res;
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}
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public static void backtrack(int[] nums, List<Integer> track) {
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// 回溯结束条件
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if (track.size() == nums.length) {
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res.add(new ArrayList<>(track));
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return;
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}
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for (int num : nums) {
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if (track.contains(num)) {
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continue;
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}
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track.add(num);
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backtrack(nums, track);
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track.remove(track.size() - 1);
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}
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}
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}
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