2510. Check if There is a Path With Equal Number of 0’s And 1’s
You are given a 0-indexed m x n binary matrix grid. You can move from a cell (row, col) to any of the cells (row + 1, col) or (row, col + 1).
Return true if there is a path from (0, 0) to (m - 1, n - 1) that visits an equal number of 0’s and 1’s. Otherwise return false.
2539. Count the Number of Good Subsequences
A subsequence of a string is good if it is not empty and the frequency of each one of its characters is the same.
Given a string s, return the number of good subsequences of s. Since the answer may be too large, return it modulo 109 + 7.
A subsequence is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters.