Distinct Moves
Given a number line from 0 to n and a string denoting a sequence of moves,
determine the number of subsequences of those moves that lead from a given point x to end
at another point y. Moves will be given as a sequence of l and r
instructions. An instruction l = left movement, so from position j the new
position is j - 1, an instruction r = right movement, so from position
j the new position would be j + 1.
For example, given a number line from 0 to 6, and a sequence of moves
rrlrr, the number of subsequences that lead from 1 to 4 on the
number line is 3.
Complete the function distinctMoves in the editor.
distinctMoves has the following parameter(s):
s: a string that represents a sequence of movesn: an integer that represents the upper bound of the number linex: an integer that represents the starting pointy: an integer that represents the ending point
Returns
int: the number of distinct subsequences modulo 10^9 + 7
s = "rrlrlr" n = 6 x = 1 y = 2 return = 7
1 <= |s| <= 10^30 <= x, y, n <= 2500
public int distinctMoves(String s, int n, int x, int y) {
// write your code here
}