47:全排列 II

LeetCode/src/main/java/leetcode/editor/cn/PermutationsIi.java

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+//给定一个可包含重复数字的序列 nums ，按任意顺序 返回所有不重复的全排列。 
+//
+// 
+//
+// 示例 1： 
+//
+// 
+//输入：nums = [1,1,2]
+//输出：
+//[[1,1,2],
+// [1,2,1],
+// [2,1,1]]
+// 
+//
+// 示例 2： 
+//
+// 
+//输入：nums = [1,2,3]
+//输出：[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
+// 
+//
+// 
+//
+// 提示： 
+//
+// 
+// 1 <= nums.length <= 8 
+// -10 <= nums[i] <= 10 
+// 
+// Related Topics 回溯算法 
+// 👍 681 👎 0
+
+package leetcode.editor.cn;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+//47:全排列 II
+public class PermutationsIi {
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new PermutationsIi().new Solution();
+        solution.permuteUnique(new int[]{1, 1, 2});
+    }
+
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class Solution {
+        boolean[] vis;
+
+        public List<List<Integer>> permuteUnique(int[] nums) {
+            List<List<Integer>> ans = new ArrayList<List<Integer>>();
+            List<Integer> perm = new ArrayList<Integer>();
+            vis = new boolean[nums.length];
+            Arrays.sort(nums);
+            backtrack(nums, ans, 0, perm);
+            return ans;
+        }
+
+        public void backtrack(int[] nums, List<List<Integer>> ans, int idx, List<Integer> perm) {
+            if (idx == nums.length) {
+                ans.add(new ArrayList<Integer>(perm));
+                return;
+            }
+            for (int i = 0; i < nums.length; ++i) {
+                if (vis[i] || (i > 0 && nums[i] == nums[i - 1] && !vis[i - 1])) {
+                    continue;
+                }
+                perm.add(nums[i]);
+                vis[i] = true;
+                backtrack(nums, ans, idx + 1, perm);
+                vis[i] = false;
+                perm.remove(idx);
+            }
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}

LeetCode/src/main/java/leetcode/editor/cn/PermutationsIi.md

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+<p>给定一个可包含重复数字的序列 <code>nums</code> ，<strong>按任意顺序</strong> 返回所有不重复的全排列。</p>
+
+<p> </p>
+
+<p><strong>示例 1：</strong></p>
+
+<pre>
+<strong>输入：</strong>nums = [1,1,2]
+<strong>输出：</strong>
+[[1,1,2],
+ [1,2,1],
+ [2,1,1]]
+</pre>
+
+<p><strong>示例 2：</strong></p>
+
+<pre>
+<strong>输入：</strong>nums = [1,2,3]
+<strong>输出：</strong>[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
+</pre>
+
+<p> </p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 <= nums.length <= 8</code></li>
+	<li><code>-10 <= nums[i] <= 10</code></li>
+</ul>
+<div><div>Related Topics</div><div><li>回溯算法</li></div></div>\n<div><li>👍 681</li><li>👎 0</li></div>