LeetCode: Permutations

一次过

 1 class Solution {

 2 public:

 3     void dfs(int dep, int maxdep, vector<int> &tmp, vector<vector<int>> &ret, vector<int> num, vector<bool> &visit) {

 4         if (dep == maxdep) {

 5             ret.push_back(tmp);

 6             return;

 7         }

 8         for (int i = 0; i < maxdep; i++) {

 9             if (!visit[i]) {

10                 visit[i] = true;

11                 tmp.push_back(num[i]);

12                 dfs(dep+1, maxdep, tmp, ret, num, visit);

13                 tmp.pop_back();

14                 visit[i] = false;

15             }

16         }

17     }

18     vector<vector<int> > permute(vector<int> &num) {

19         // Start typing your C/C++ solution below

20         // DO NOT write int main() function

21         sort(num.begin(), num.end());

22         int size = num.size();

23         vector<int> tmp;

24         vector<vector<int>> ret;

25         vector<bool> visit(size, false);

26         dfs(0, size, tmp, ret, num, visit);

27         return ret;

28     }

29 };

 推荐下一段代码

 1 class Solution {

 2 public:

 3     void dfs(vector<int> &num, vector<vector<int> > &ans, int k) {

 4         if (k == num.size()) {

 5             ans.push_back(num);

 6             return;

 7         }

 8         for (int i = k; i < num.size(); ++i) {

 9             swap(num[i], num[k]);

10             dfs(num, ans, k+1);

11             swap(num[i], num[k]);

12         }

13     }

14     vector<vector<int> > permute(vector<int> &num) {

15         vector<vector<int> > ans;

16         if (num.size() == 0) return ans;

17         sort(num.begin(), num.end());

18         dfs(num, ans, 0);

19         return ans;

20     }

21 };

 C#

 1 public class Solution {

 2     public List<List<int>> Permute(int[] nums) {

 3         List<List<int>> ans = new List<List<int>>();

 4         if (nums.Length == 0) return ans;

 5         Array.Sort(nums);

 6         dfs(nums, ref ans, 0);

 7         return ans;

 8     }

 9     public void dfs(int[] nums, ref List<List<int>> ans, int k) {

10         if (k == nums.Length) {

11             ans.Add(new List<int>(nums));

12             return;

13         }

14         for (int i = k; i < nums.Length; i++) {

15             int tmp = nums[i];

16             nums[i] = nums[k];

17             nums[k] = tmp;

18             dfs(nums, ref ans, k+1);

19             tmp = nums[i];

20             nums[i] = nums[k];

21             nums[k] = tmp;

22         }

23     }

24 }

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