115. Distinct Subsequences

public class Solution { public int numDistinct(String s, String t) { int[][] nums = new int[t.length()+1][s.length()+1]; for(int i = 0; i< s.length()+1;i++) { nums[0][i] = 1; } for(int i = 0; i < t.length();i++) { for(int j =0; j < s.length(); j++) { if(t.charAt(i) == s.charAt(j)) { nums[i+1][j+1] = nums[i][j] + nums[i+1][j]; }else { nums[i+1][j+1] = nums[i+1][j]; } } } return nums[t.length()][s.length()]; } }