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48 lines
1.1 KiB
Markdown
48 lines
1.1 KiB
Markdown
## 题目地址
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https://leetcode-cn.com/problems/permutations-ii/
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## 思路
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i > 0 && nums[i] == nums[i-1] && used[i-1] == false
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这是最高效的，可以用 1 1 1 1 1 跑一个样例试试
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## C++代码
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```
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class Solution {
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private:
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vector<vector<int>> result;
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void backtracking (vector<int>& nums, vector<int>& vec, vector<bool>& used) {
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// 此时说明找到了一组
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if (vec.size() == nums.size()) {
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result.push_back(vec);
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return;
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}
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for (int i = 0; i < nums.size(); i++) {
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if (i > 0 && nums[i] == nums[i-1] && used[i-1] == false) {
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continue;
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}
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if (used[i] == false) {
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used[i] = true;
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vec.push_back(nums[i]);
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backtracking(nums, vec, used);
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vec.pop_back();
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used[i] = false;
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}
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}
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}
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public:
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vector<vector<int>> permuteUnique(vector<int>& nums) {
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sort(nums.begin(), nums.end());
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vector<bool> used(nums.size(), false);
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vector<int> vec;
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backtracking(nums, vec, used);
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return result;
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}
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};
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```
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