title: Longest Subsequence Such That Difference Between Adjacents Is One
signature: function longestSubsequenceSuchThatDifferenceBetweenAdjacentsIsOne(arr, n) {
test_code: 
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  function convertToString(value) {
      return JSON.stringify(value, function (key, val) {
          if (val instanceof Set) {
              return Array.from(val);
          } return val;});
  }
  
  function validateSolution(actual, expected){
      return convertToString(actual)===convertToString(expected);
  }
  
  function driver(arr, n, expected){
      try{
          if (validateSolution(PLACEHOLDER_FN_NAME(arr, n),expected)){
              return "PASSED";
          }
          return "FAILED";
      } catch (error) {
        return error.name;
      }
      
  }
      
  function main(){
    let result = '';
    result = driver([2, 13, 15, 17, 18, 20, 22, 24, 28, 34, 37, 43, 46, 47, 49, 51, 52, 54, 58, 64, 65, 77, 78, 79, 87, 90, 92, 93, 94, 97], 23, 2);
    console.log(`TEST-0...${result}`);
  
    result = driver([-86, -56, 76, 86, 42, -40, 8, 34, -48, -54, -80, 6, 42, 48, 76, -26, 6], 15, 1);
    console.log(`TEST-1...${result}`);
  
    result = driver([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1], 16, 2);
    console.log(`TEST-2...${result}`);
  
    result = driver([5, 22, 15, 26, 29, 47, 22], 5, 1);
    console.log(`TEST-3...${result}`);
  
    result = driver([-90, -84, -76, -76, -74, -74, -66, -58, -58, -56, -56, -44, -38, -36, -34, -32, -16, -10, 2, 6, 24, 24, 24, 34, 36, 54, 60, 68, 70, 76, 88], 17, 1);
    console.log(`TEST-4...${result}`);
  
    result = driver([0, 1, 1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 1], 26, 12);
    console.log(`TEST-5...${result}`);
  
    result = driver([1, 3, 12, 12, 12, 12, 14, 17, 18, 19, 23, 27, 28, 30, 35, 38, 42, 44, 45, 48, 52, 59, 61, 64, 65, 69, 73, 76, 77, 82, 83, 85, 87, 99], 23, 3);
    console.log(`TEST-6...${result}`);
  
    result = driver([-54, -20, 24, -78, -58, 64, 34, 70, -36, -24], 8, 1);
    console.log(`TEST-7...${result}`);
  
    result = driver([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1], 27, 2);
    console.log(`TEST-8...${result}`);
  
    result = driver([5, 35, 75, 21, 82, 32, 28, 53, 20, 27, 42, 92, 32, 70, 81, 75, 72, 66, 97, 60, 11, 83, 14, 30, 5, 68, 17, 27, 62, 86, 26, 20, 97, 91, 44, 69], 20, 2);
    console.log(`TEST-9...${result}`);
  
    process.exit(0);
  };
  
  if (require.main === module) {
    main();
  }
source_py: def longest_subsequence_such_that_difference_between_adjacents_is_one(arr, n):
      dp = [1 for i in range(n)]
      for i in range(n):
          for j in range(i):
              if ((arr[i] == (arr[j] + 1)) or (arr[i] == (arr[j] - 1))):
                  dp[i] = max(dp[i], (dp[j] + 1))
      result = 1
      for i in range(n):
          if (result < dp[i]):
              result = dp[i]
      return result
source_cpp: int longest_subsequence_such_that_difference_between_adjacents_is_one(vector<int> arr, int n) {
    int dp [ n ];
    for ( int i = 0;
    i < n;
    i ++ ) dp [ i ] = 1;
    for ( int i = 1;
    i < n;
    i ++ ) {
      for ( int j = 0;
      j < i;
      j ++ ) {
        if ( ( arr [ i ] == arr [ j ] + 1 ) || ( arr [ i ] == arr [ j ] - 1 ) ) dp [ i ] = max ( dp [ i ], dp [ j ] + 1 );
      }
    }
    int result = 1;
    for ( int i = 0;
    i < n;
    i ++ ) if ( result < dp [ i ] ) result = dp [ i ];
    return result;
  }