class Solution {
public:
vector<int> findDuplicates(vector<int>& nums) {
int n = nums.size();
vector<int>res;
for(int i=0;i<n;i++)
{
int p = abs(nums[i]) - 1;
nums[p] *= -1;
if(nums[p] > 0) res.push_back(abs(nums[i]));
}
return res;
}
};
vcetor int res 这个额外数组空间为O(1),不应该O(n)吗,不对把