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Fabricio Loupias
Asked: 2020-08-18 16:06:45 +0800 CST 2020-08-18 16:06:45 +0800 CST

Javascript math exercise

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What would be the correct way to solve this problem using Javascript?

You are provided with the following information:

● January 1, 1900 was a Monday.
● Thirty days have September, April, June and November.
● February is twenty-eight (and in leap years, twenty-nine).
● The rest have thirty-one.

Note: A leap year occurs in any year divisible by 4, but not in a century unless it is divisible by 400.

How many Sundays fell on the first day of the month during the 20th century (January 1, 1901 to December 31, 2000)?

javascript

2 Answers

  1. Greetings friend, your problem is really simple. I won't give you much code because I'm on the phone and it's complicated, but I'll try to make you understand me. You need a for loop and three switches. You also need to know how many days there are from the start date to the end date. end, January 1, 1901 to December 31, 2000 in this case, which is the closest leap year to the start date (in the example I will assume that the leap year is the same start date) some if conditionals and variables correct e.g.

    var nroDias = //total numero de dias,
nroMes=0,
nroAño=0,
diaSemana,
x=0, y=0, z=0;

for(x=1;x《=nroDias;x++){
    y++;
    z++;
    swich(y){
        case 1:diaSemana='lunes';
        break;
        case 2:diaSemana='martes';
        break;
        //y asi hasta completar los siete dias y en el dia 7 llevas la variable y =0 para que se repita el ciclo
    }
}

    The same principle you apply to find the leap year (if(year==4){leap=si; year=0;} and the number of the month only applies a little logic and with an if (dayOfMonth ==1 && dayWeek= ='Sunday'){variableWhatISeek++} and everything inside the for loop. Good luck with what you do

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  2. Best Answer

    This is my attempt, the first time I do it, I hope it works for you:

    function Calcular()
{
  //DECLARO LAS VARIABLES
  var dateInicio  = new Date("01"+' '+"January"+', '+"1901"+' 12:00:00');
  var dateFinal = new Date("31"+' '+"December"+', '+"2000"+' 12:00:00');
  var dateAux = new Date();
  var cantidadMesInicio = dateInicio.getMonth();
  var cantidadAnoInicio = dateInicio.getFullYear();
  var cantidadDias = 0;
  var cantidadDomingos = 0;
  //WHILE PARA ITERAR DESDE LA FECHA INICIO HASTA LA FECHA FINAL
  while (dateInicio <= dateFinal)
  {
    //SWITCH PARA VERIFICAR EN CUAL MES ESTA LA FECHA INICIO
    switch (cantidadMesInicio)
    {
      case (8 || 3 || 5 || 10): //SEPTIEMBRE, ABRIL, JUNIO, NOVIEMBRE
        cantidadDias = 30;
        break;
      case 1: //FEBRERO
        cantidadDias = 28;
        //IF PARA SABER SI ES AÑO BISIESTO
        if ((cantidadAnoInicio % 4 === 0 && cantidadAnoInicio % 100 !== 0) || (cantidadAnoInicio % 400 === 0))
          cantidadDias = 29;
        break;
      default:  //RESTO DE LOS MESES
        cantidadDias = 31;
        break;
    }
    //SUMO LA CANTIDAD DE DIAS A LA FECHA INICIO Y LO SETEO A UNA FECHA AUXILIAR
    dateAux.setDate(dateInicio.getDate() + cantidadDias);
    //WHILE PARA ITERAR DESDE FECHA INICIO HASTA LA FECHA AUXILIAR
    while (dateInicio <= dateAux)
    {
      //IF PARA SABER SI EL DÍA ES DOMINGO Y CAE EL PRIMER DÍA DEL MES
      if (dateInicio.getDay() === 0 && dateInicio <= dateFinal && dateInicio.getDate() === 1)
        cantidadDomingos++;
      //SUMO 1 DIA A LA FECHA INICIO Y LO SETEO A LA FECHA INICIO
      dateInicio.setDate(dateInicio.getDate() + 1);
    }
    //OBTENGO EL MES Y EL AÑO PARA CONTINUAR CON EL WHILE
    cantidadMesInicio = dateInicio.getMonth();
    cantidadAnoInicio = dateInicio.getFullYear();
  }
  alert("Cantidad de domingos: " + cantidadDomingos);
};
    <input type="button" onclick="Calcular()" value="Calcular">

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