Leetcode Problem 2083. Substrings That Begin and End With the Same Letter

Algorithm\n1. Initialize a counter to keep track of the frequency of each character.\n2. Iterate over each character in the string s and increment its count in the counter.\n3. Initialize a variable result to store the total number of substrings.\n4. Iterate over the counter and for each character frequency n, add n*(n+1)/2 to result.\n5. Return result as the final answer.\n