Dominant Grade

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Problem statement

An automated classroom assessment system determines a class's overall performance based on a string of individual student grades. The grades are 'A', 'B', 'C', 'D', 'E', 'F', with a strict precedence order: A > B > C > D > E > F.


The final grade is determined by comparing the total count of high-ranking grades against the total count of low-ranking grades.

1) High Group: Consists of grades 'A', 'B', and 'C'.

2) Low Group: Consists of grades 'D', 'E', and 'F'.


First, calculate the total score for each group:

high_score = count('A') + count('B') + count('C')

low_score = count('D') + count('E') + count('F')


The final dominant grade is determined by the following rules:

If high_score > low_score, the winner is the highest-ranking grade that is present in the High Group (check for 'A' first, then 'B', then 'C').

If low_score > high_score, the winner is the highest-ranking grade that is present in the Low Group (check for 'D' first, then 'E', then 'F').

If high_score == low_score (a tie), the winner is the highest-ranking grade present in the entire class.


Your task is to implement a function that takes the string of grades and returns the single character representing the final dominant grade.


Detailed explanation ( Input/output format, Notes, Images )
Input Format: 
The first line contains a single integer T, the number of test cases.

Each of the next T lines contains a single string grades.


Output Format: 
For each test case, print a single character representing the final dominant grade on a new line.
Sample Input 1:
3
AAABBC
ABFFFF
BCDE


Sample Output 1:
A
F
B


Explanation for Sample 1:
Test Case 1 (AAABBC): High group ('A','B','C') count = 3+2+1=6. Low group count = 0. High group wins. The highest grade present in the high group is 'A'.
Test Case 2 (ABFFFF): High group ('A','B') count = 1+1=2. Low group ('F') count = 4. Low group wins. The highest grade present in the low group is 'F'.
Test Case 3 (BCDE): High group ('B','C') count = 1+1=2. Low group ('D','E') count = 1+1=2. It's a tie. The highest grade present in the entire class is 'B'.


Expected Time Complexity:
The expected time complexity is O(N).


Constraints:
1 <= T <= 1000
1 <= length of grades string <= 10^5
The total length of all grade strings over all test cases will not exceed 5 * 10^5.
Approaches (1)
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Dominant Grade
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