simple_encryption

function enkripsi (input){
  var L = input.length
  var data_before = []
  var data_after = []
  var square = 0
  var M = L
  var result = []
  var check_string = true
  
  // cek string
  for(var i = 0 ; i < input.length ; i++){
    if(input[i].charCodeAt() < 65 || (input[i].charCodeAt() > 90 && input[i].charCodeAt() < 97) || input[i].charCodeAt() > 122){
      check_string = false
    }
  }
  
  if(check_string === false){
    return "input must string"
  }else if(input < 1 || input > 100){
    return "input must in range 1 - 100"
  }else{
    while(Math.sqrt(M) % 1 != 0){
      M++
    }

    square = Math.sqrt(M)
  
    // fill data before encryption
    for(var i = 0 ; i < square ; i++){
      data_before[i] = []
      for(var j = i*square ; j < (i*square)+square ; j++){
        if(input[j] === undefined){
          data_before[i].push("*")
        }else{
          data_before[i].push(input[j])
        }
      }
    }
    
    // fill data after encryption
    for(var i = 0 ; i < square ; i++){
      data_after[i] = []
      for(var j = 0 ; j < square; j++){
           data_after[i][j] = data_before[square - j - 1][i]
      }
    }
    
    // result (array)
    for(var i = 0 ; i < square ; i++){
      for(var j = 0 ; j < square; j++){
           if(data_after[i][j] !== "*"){
             result.push(data_after[i][j])
           }
      }
    }
     
    //result to string
    result = result.join("")
    
    return result
  }
}

console.log(enkripsi("akucintakamu"))
console.log(enkripsi("maafAkuenggak"))