Permutations
Given a collection of numbers, return all possible permutations.
For example,[1,2,3]
have the following permutations:[1,2,3]
, [1,3,2]
, [2,1,3]
, [2,3,1]
,
[3,1,2]
, and [3,2,1]
.
Permutations II
Given a collection of numbers that might contain duplicates, return all possible unique permutations.
For example,[1,1,2]
have the following unique permutations:[1,1,2]
, [1,2,1]
, and [2,1,1]
.
思路:
反复生成permutation即可。生成permutation的思路可以看这里。当然题解里就用std::next_permutation作弊了。
题解:
class Solution { public: vector<vector<int> > permuteUnique(vector<int> &num) { vector<vector<int>> ret; sort(begin(num), end(num)); ret.push_back(num); while(next_permutation(begin(num), end(num))) ret.push_back(num); return ret; } };