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Merge pull request #876 from Younglesszzz/master
更新回溯的另一种写法 全排列Ⅱ Java版本
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@ -249,6 +249,45 @@ used数组可是全局变量,每层与每层之间公用一个used数组,所
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Java:
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**47.全排列II**
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```java
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class Solution {
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private List<List<Integer>> res = new ArrayList<>();
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private List<Integer> path = new ArrayList<>();
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private boolean[] used = null;
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public List<List<Integer>> permuteUnique(int[] nums) {
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used = new boolean[nums.length];
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Arrays.sort(nums);
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backtracking(nums);
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return res;
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}
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public void backtracking(int[] nums) {
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if (path.size() == nums.length) {
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res.add(new ArrayList<>(path));
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return;
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}
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HashSet<Integer> hashSet = new HashSet<>();//层去重
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for (int i = 0; i < nums.length; i++) {
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if (hashSet.contains(nums[i]))
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continue;
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if (used[i] == true)//枝去重
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continue;
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hashSet.add(nums[i]);//记录元素
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used[i] = true;
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path.add(nums[i]);
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backtracking(nums);
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path.remove(path.size() - 1);
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used[i] = false;
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}
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}
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}
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```
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Python:
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