I use the following method to remove duplicates instead of a set or hashmap. But it can't AC. Can someone explain me why this is wrong? Better with an example. Thanks!

```
void dfs(vector<int>& nums, int curr, vector<int>& path, vector<vector<int> >& result) {
if (path.size() >= 2) {
result.push_back(path);
}
if (curr == nums.size())
return;
int last;
for (int i = curr; i < nums.size(); i++) {
if (i > curr && nums[i] == last) continue; //to avoid adding the same element in the same level
if (path.size() == 0 || nums[i] >= path.back()) {
path.push_back(nums[i]);
last = nums[i];
dfs(nums, i+1, path, result);
path.pop_back();
}
}
}
vector<vector<int>> findSubsequences(vector<int>& nums) {
vector<int> path;
vector<vector<int> > result;
if (nums.empty() || nums.size() <= 1)
return result;
dfs(nums, 0, path, result);
return result;
}
```