title: Count Distinct Occurrences As A Subsequence
signature: countDistinctOccurrencesAsASubsequence(s, t) {
test_code: import 'dart:convert';
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  bool validateSolution(int actual, int expected){
      return actual.toString() == expected.toString();
  }
  
  String driver(s, t, int expected){
      try
      {
          if (validateSolution(PLACEHOLDER_FN_NAME(s, t), expected)){
              return "PASSED";
          }
          return "FAILED";
      }catch(exception_object){
          return exception_object.runtimeType.toString();
      }
  }
  
  int main() {
  
      print("TEST-0...${driver(
          "banana", "ban", 
          3)
      }");
  
      print("TEST-1...${driver(
          "49597223", "42", 
          2)
      }");
  
      print("TEST-2...${driver(
          "1000010000011", "010", 
          20)
      }");
  
      print("TEST-3...${driver(
          "BTlzufK", "EpsVuzP lf", 
          0)
      }");
  
      print("TEST-4...${driver(
          "3474007", "370", 
          2)
      }");
  
      print("TEST-5...${driver(
          "0010", "00000", 
          0)
      }");
  
      print("TEST-6...${driver(
          "dKHhoTD", "doT", 
          1)
      }");
  
      print("TEST-7...${driver(
          "9123259723", "123", 
          4)
      }");
  
      print("TEST-8...${driver(
          "11001000111110", "0", 
          6)
      }");
  
      print("TEST-9...${driver(
          "iY WJlIZ", "iI", 
          1)
      }");
  
      return 0;
  }
source_py: def count_distinct_occurrences_as_a_subsequence(S, T):
      m = len(T)
      n = len(S)
      if (m > n):
          return 0
      mat = [[0 for _ in range((n + 1))] for __ in range((m + 1))]
      for i in range(1, (m + 1)):
          mat[i][0] = 0
      for j in range((n + 1)):
          mat[0][j] = 1
      for i in range(1, (m + 1)):
          for j in range(1, (n + 1)):
              if (T[(i - 1)] != S[(j - 1)]):
                  mat[i][j] = mat[i][(j - 1)]
              else:
                  mat[i][j] = (mat[i][(j - 1)] + mat[(i - 1)][(j - 1)])
      return mat[m][n]
source_cpp: int count_distinct_occurrences_as_a_subsequence(string S, string T) {
    int m = T . length ( ), n = S . length ( );
    if ( m > n ) return 0;
    int mat [ m + 1 ] [ n + 1 ];
    for ( int i = 1;
    i <= m;
    i ++ ) mat [ i ] [ 0 ] = 0;
    for ( int j = 0;
    j <= n;
    j ++ ) mat [ 0 ] [ j ] = 1;
    for ( int i = 1;
    i <= m;
    i ++ ) {
      for ( int j = 1;
      j <= n;
      j ++ ) {
        if ( T [ i - 1 ] != S [ j - 1 ] ) mat [ i ] [ j ] = mat [ i ] [ j - 1 ];
        else mat [ i ] [ j ] = mat [ i ] [ j - 1 ] + mat [ i - 1 ] [ j - 1 ];
      }
    }
    return mat [ m ] [ n ];
  }