Positional Vote Ranking

You are given an array votes of ballots from an election among a fixed set of candidates, each named by an uppercase letter. Each ballot is a string ranking all candidates from most to least preferred, and every ballot ranks the same set of candidates.

The final order is decided positionally:

• candidates are compared by their number of first-place votes (more is better);
• ties are broken by second-place votes, then third-place votes, and so on;
• candidates tied at every position are ordered alphabetically.

Return a string of all candidates in final order.

Examples

Example 1

Input: votes = ["ABC", "ACB", "ABC", "ACB", "ACB"]
Output: "ACB"
Explanation: A is ranked first by all 5 voters. C beats B on second-place
votes, 3 to 2.

Example 2

Input: votes = ["WXYZ", "XYZW"]
Output: "XWYZ"
Explanation: X and W tie on first-place votes; X wins on second-place votes.

Example 3

Input: votes = ["ZMNAGUEDSJYLBOPHRQICWFXTVK"]
Output: "ZMNAGUEDSJYLBOPHRQICWFXTVK"