Dense Ranks Preserving Value Order and Equality

### Problem Replace each value by its smallest possible positive rank: equal values share a rank, and a larger value must have a larger rank. Return ranks in the original position order. The empty array is allowed. ```cpp class Solution { public: vector<int> arrayRankTransform(vector<int>& arr); }; ``` ### Examples **Example 1:** ```text Input: arr = [7,-2,7,0] Output: [3,1,3,2] Explanation: The distinct sorted values-2,0,7 receive ranks1,2,3. ``` **Example 2:** ```text Input: arr = [] Output: [] Explanation: There are no positions to rank. ``` ### Constraints - Array length is between 0 and 100000. - Each original value is an integer in `[-1000000000,1000000000]`. ### Contract considerations Keep the vector-reference callable; the reference replaces and returns that input array. ```hint Read the boundary condition Check equal values, negative values, and an empty input. Ranks must remain in the original position order and be as small as permitted. ``` ### Boundary reminders Keep the vector-reference callable; the reference replaces and returns that input array.