title: Count Ofdifferent Ways Express N Sum 1 3 4
signature: pub fn count_ofdifferent_ways_express_n_sum_1_3_4(n: i32) -> i64 {
test_code: use std::collections::HashMap;
  use std::collections::HashSet;
  use std::cmp::*;
  use std::collections::*;
  use std::fmt::*; 
  
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  pub fn validate_solution(actual: i64, expected: i64)->bool{
  return actual==expected
  }
  pub fn driver(n: i32, expected: i64)->String{
      if validate_solution(PLACEHOLDER_FN_NAME(n), expected) {
        return "PASSED".to_string();
      };
      return "FAILED".to_string();
  
  }
  
  fn main() {
      println!("TEST-0...{}", driver(
        44, 
        821223649
      ));
      
      println!("TEST-1...{}", driver(
        9, 
        40
      ));
      
      println!("TEST-2...{}", driver(
        19, 
        4895
      ));
      
      println!("TEST-3...{}", driver(
        10, 
        64
      ));
      
      println!("TEST-4...{}", driver(
        78, 
        10472279279564025
      ));
      
      println!("TEST-5...{}", driver(
        70, 
        222915410843904
      ));
      
      println!("TEST-6...{}", driver(
        81, 
        44361286907595736
      ));
      
      println!("TEST-7...{}", driver(
        81, 
        44361286907595736
      ));
      
      println!("TEST-8...{}", driver(
        49, 
        9107509825
      ));
      
  }
source_py: def count_ofdifferent_ways_express_n_sum_1_3_4(n):
      DP = [0 for i in range(0, (n + 1))]
      DP[0] = DP[1] = DP[2] = 1
      DP[3] = 2
      for i in range(4, (n + 1)):
          DP[i] = ((DP[(i - 1)] + DP[(i - 3)]) + DP[(i - 4)])
      return DP[n]
source_cpp: int count_ofdifferent_ways_express_n_sum_1_3_4(int n) {
    int DP [ n + 1 ];
    DP [ 0 ] = DP [ 1 ] = DP [ 2 ] = 1;
    DP [ 3 ] = 2;
    for ( int i = 4;
    i <= n;
    i ++ ) DP [ i ] = DP [ i - 1 ] + DP [ i - 3 ] + DP [ i - 4 ];
    return DP [ n ];
  }