title: Count Distinct Occurrences As A Subsequence
signature: function countDistinctOccurrencesAsASubsequence(s: string, t: string): number {
test_code: 
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  function convertToString(value: any): string{
      return JSON.stringify(value, function (key, val) {
          if (val instanceof Set) {
              return Array.from(val);
          } return val;});
  }
  
  function validateSolution(actual: number, expected: number): boolean {
      return convertToString(actual) === convertToString(expected);
  }
  
  function driver(s: string, t: string, expected:number): string {
      try{
          if (validateSolution(PLACEHOLDER_FN_NAME(s, t),expected)){
              return "PASSED";
          }
          return "FAILED";
      } catch (error) {
        return error.name;
      }
      
  }
      
  function main(){
    let result = '';
    result = driver("banana", "ban", 3);
    console.log(`TEST-0...${result}`);
  
    result = driver("49597223", "42", 2);
    console.log(`TEST-1...${result}`);
  
    result = driver("1000010000011", "010", 20);
    console.log(`TEST-2...${result}`);
  
    result = driver("BTlzufK", "EpsVuzP lf", 0);
    console.log(`TEST-3...${result}`);
  
    result = driver("3474007", "370", 2);
    console.log(`TEST-4...${result}`);
  
    result = driver("0010", "00000", 0);
    console.log(`TEST-5...${result}`);
  
    result = driver("dKHhoTD", "doT", 1);
    console.log(`TEST-6...${result}`);
  
    result = driver("9123259723", "123", 4);
    console.log(`TEST-7...${result}`);
  
    result = driver("11001000111110", "0", 6);
    console.log(`TEST-8...${result}`);
  
    result = driver("iY WJlIZ", "iI", 1);
    console.log(`TEST-9...${result}`);
  
  };
  
  main();
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 ];
  }