vector<vector<int>> permuteUnique(vector<int>& nums) {
sort(nums.begin(), nums.end());
vector<vector<int>> res;
vector<int> perm;
permuteUniqueHelper(res, nums, perm);
return res;
}
vector<vector<int> > permuteUniqueSub(vector<int> &num) {
sort(num.begin(),num.end());//sort the original array.
vector<bool> used(num.size(),false);
vector<int> subans;
vector<vector<int>> ans;
permuteUniqueHelper(num,subans,used,ans);
return ans;
}
/**
* @param nums: A list of integers.
* @return: A list of unique permutations.
*/
vector<vector<int>> permuteUnique(vector<int> &nums) {
vector<vector<int>> result;
vector<bool> used(nums.size(), false);
vector<int> ans;
sort(nums.begin(), nums.end());
permuteUniqueHelper(nums, &used, &ans, &result);
return result;
}
void permuteUniqueHelper(vector<int> &num,vector<int> & subans,vector<bool> &used, vector<vector<int>> & ans){
if (subans.size() == num.size()) {
ans.push_back(subans);
return;
}
for (int i = 0; i < num.size(); i++) {
if (used[i] || (i != 0 && num[i] == num[i - 1] && used[i - 1])) continue;
used[i] = true;
subans.push_back(num[i]);
permuteUniqueHelper(num,subans,used,ans);
used[i] = false;
subans.pop_back();
}
}
void permuteUniqueHelper(vector<vector<int>>& res, vector<int>& nums, vector<int>& perm) {
if(nums.empty()) {
res.push_back(perm);
}
for(int i = 0; i < nums.size(); i++) {
if(i > 0 && nums[i] == nums[i - 1]) {
continue;
}
perm.push_back(nums[i]);
nums.erase(nums.begin() + i);
permuteUniqueHelper(res, nums, perm);
nums.insert(nums.begin() + i, perm.back());
perm.pop_back();
}
}
void permuteUniqueHelper(const vector<int> &A, vector<bool> *used,
vector<int> *ans, vector<vector<int>> *result) {
if (ans->size() == A.size()) {
result->emplace_back(*ans);
return;
}
for (size_t i = 0; i < A.size(); ++i) {
if ((*used)[i] || (i != 0 && A[i - 1] == A[i] && !(*used)[i - 1])) {
continue;
}
(*used)[i] = true;
ans->emplace_back(A[i]);
permuteUniqueHelper(A, used, ans, result);
ans->pop_back();
(*used)[i] = false;
}
}
vector<vector<int>> SubSetTest::permuteUnique( const vector<int>& num )
{
vector<vector<int>> rst;
if (num.size() == 0)
{
return rst;
}
vector<int> list;
vector<int> visited;
visited.insert(visited.begin(), num.size(), 0);
vector<int> tmpNum = num; //attention: const can't be modified
sort(tmpNum.begin(),tmpNum.end(),less<int>()); //attention: ascending greater<int>() descending
permuteUniqueHelper(rst, list, visited, num);
return rst;
}
void SubSetTest::permuteUniqueHelper( vector<vector<int>>& rst, vector<int>& list, vector<int>& visited, const vector<int>& num )
{
if (list.size() == num.size())
{
rst.push_back(list);
return; //attention
}
for (int i = 0; i < num.size(); ++i)
{
if (visited[i] == 1 || (i != 0 && num[i] == num[i - 1] && visited[i - 1] == 0)){
continue;
}
visited[i] = 1;
list.push_back(num[i]);
permuteUniqueHelper(rst, list, visited, num);
list.pop_back();
visited[i] = 0; //visited[visited.size() - 1] = 0; //attention: wrong
}
}
