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The task demonstrates how postfix/prefix forms can lead to different results when used in comparisons. | ||
La tarea demuestra como las formas de sufjio y prefijo pueden llevar a diferentes resultado cuando son usadas en comparaciones. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. como -> cómo |
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1. **From 1 to 4** | ||
1. **Del 1 al 4** | ||
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```js run | ||
let i = 0; | ||
while (++i < 5) alert( i ); | ||
``` | ||
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The first value is `i = 1`, because `++i` first increments `i` and then returns the new value. So the first comparison is `1 < 5` and the `alert` shows `1`. | ||
El primer valor es `i = 1`, porque primero `++i` incrementa `i` y entonces retorna el valor nuevo. Asi que la primera comparación es `1 < 5` y el `alert` muestra `1`. | ||
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Then follow `2, 3, 4…` -- the values show up one after another. The comparison always uses the incremented value, because `++` is before the variable. | ||
Entonces siguen `2, 3, 4…` -- los valores son mostrados uno tras de otro. La comparación siempre usa el valor incrementado, porque `++` esta antes de la variable. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Sugiero: "...mostrados uno tras otro. La comparación siempre usa el valor incrementado porque |
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Finally, `i = 4` is incremented to `5`, the comparison `while(5 < 5)` fails, and the loop stops. So `5` is not shown. | ||
2. **From 1 to 5** | ||
Finalmente, `i = 4` es incrementada a `5`, la comparación `while(5 < 5)` falla, y el bucle se detiene. Asi que `5` no es mostrado. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Asi -> Así |
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2. **Del 1 al 5** | ||
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```js run | ||
let i = 0; | ||
while (i++ < 5) alert( i ); | ||
``` | ||
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The first value is again `i = 1`. The postfix form of `i++` increments `i` and then returns the *old* value, so the comparison `i++ < 5` will use `i = 0` (contrary to `++i < 5`). | ||
El primer valor es de nuevo `i = 1`. La forma del sufijo de `i++` incrementa `i` y entonce retorna el valor *viejo*, asi que la comparación `i++ < 5` usara `i = 0` (contrario a `++i < 5`). | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. asi -> así |
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But the `alert` call is separate. It's another statement which executes after the increment and the comparison. So it gets the current `i = 1`. | ||
Pero la llamada a `alert` esta separda. Es otra declaración la cual se ejecuta luego del increment y la comparación. Asi que obtiene el `i = 1` actual. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. esta->está |
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Then follow `2, 3, 4…` | ||
Luego siguen `2, 3, 4…` | ||
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Let's stop on `i = 4`. The prefix form `++i` would increment it and use `5` in the comparison. But here we have the postfix form `i++`. So it increments `i` to `5`, but returns the old value. Hence the comparison is actually `while(4 < 5)` -- true, and the control goes on to `alert`. | ||
Vamos a parar en `i = 4`. La forma del prefijo `++i` lo incrementaria y usaria `5` en la comparación. Pero aqui tenemos la forma del sufijo `i++`. Asi que incrementa `i` a `5`, pero retorna el valor viejo. Por lo tanto, la comparación es en realidad `while(4 < 5)` -- verdadero, y el control sigue a `alert`. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Me parece que quedaría mejor "Detengámonos en |
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The value `i = 5` is the last one, because on the next step `while(5 < 5)` is false. | ||
El valor `i = 5` es el último, porque el siguiente paso `while(5 < 5)` es falso. |
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--- | ||
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# Which values does the while loop show? | ||
# ¿Cuál valor es mostrado por el bucle while? | ||
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For every loop iteration, write down which value it outputs and then compare it with the solution. | ||
Para cada iteración del bucle, escribe cual valor sera impreso y entonces comparalo con la solución. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Quedaría mejor "Para cada iteración del bucle, escribe qué valor será mostrado y luego compáralo con la solución." |
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Both loops `alert` the same values, or not? | ||
¿Para cada bucle se alertan los mismos valores o no? | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Me parece que quedaría mejor "Ambos bucles ¿ |
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1. The prefix form `++i`: | ||
1. La forma de prefijo `++i`: | ||
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```js | ||
let i = 0; | ||
while (++i < 5) alert( i ); | ||
``` | ||
2. The postfix form `i++` | ||
2. La forma de sufijo `i++` | ||
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```js | ||
let i = 0; | ||
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--- | ||
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# Which values get shown by the "for" loop? | ||
# ¿Qué valores seran mostrados por el bucle "for"? | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. seran->serán |
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For each loop write down which values it is going to show. Then compare with the answer. | ||
Para cada bucle anota que valores va a mostrar. Entonces compara con la respuesta. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. No hace falta una traducción textual, quedaría mejor: |
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Both loops `alert` same values or not? | ||
¿Ambos bucles alertan los mismos valores o no? | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more.
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1. The postfix form: | ||
1. La forma del sufijo: | ||
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```js | ||
for (let i = 0; i < 5; i++) alert( i ); | ||
``` | ||
2. The prefix form: | ||
2. La forma del prefijo: | ||
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```js | ||
for (let i = 0; i < 5; ++i) alert( i ); | ||
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} | ||
``` | ||
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We use the "modulo" operator `%` to get the remainder and check for the evenness here. | ||
Usamos el operador modulo `%` para conseguir el residuo y que los valores son pares. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Usamos el operador "módulo" |
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--- | ||
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# Output even numbers in the loop | ||
# Produce números pares en el bucle | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Produce->Muestra |
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Use the `for` loop to output even numbers from `2` to `10`. | ||
Usa el bucle `for` para producir números pares del `2` al `10`. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. "...para mostrar..." |
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[demo] |
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```js run | ||
let i = 0; | ||
while (i < 3) { | ||
alert( `number ${i}!` ); | ||
alert( `número ${i}!` ); | ||
i++; | ||
} | ||
``` | ||
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--- | ||
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# Replace "for" with "while" | ||
# Reemplaza "for" por "while" | ||
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Rewrite the code changing the `for` loop to `while` without altering its behavior (the output should stay same). | ||
Reescribe el código cambiando el bucle `for` a `while` sin alterar su comportamient (la salida deberia ser la misma). | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. comportamientO |
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```js run | ||
for (let i = 0; i < 3; i++) { | ||
alert( `number ${i}!` ); | ||
alert( `número ${i}!` ); | ||
} | ||
``` | ||
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let num; | ||
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do { | ||
num = prompt("Enter a number greater than 100?", 0); | ||
num = prompt("Ingresa un número mayor a 100", 0); | ||
} while (num <= 100 && num); | ||
``` | ||
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The loop `do..while` repeats while both checks are truthy: | ||
El bucle `do..while` se repite mientras ambas comprobaciones sean valores verdaderos: | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Podría quedar mejor "mientras ambas condiciones sean verdaderas:" o no? |
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1. The check for `num <= 100` -- that is, the entered value is still not greater than `100`. | ||
2. The check `&& num` is false when `num` is `null` or a empty string. Then the `while` loop stops too. | ||
1. La comprobación para `num <= 100` -- eso es, el valor ingresado aún no es mayor que `100`. | ||
2. La comprobación `&& num` es falsa cuando `num` es `null` o una cadena de texto vacia. Entonces el bucle `while` se detiene tambien. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. "La condición |
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P.S. If `num` is `null` then `num <= 100` is `true`, so without the 2nd check the loop wouldn't stop if the user clicks CANCEL. Both checks are required. | ||
PD. Si `num` es `null` entonces `num <= 100` es `true`, asi que sin la segunda comprabación el bucle no se detendria si el usuario hace click en CANCELAR. Ambas comprobaciones son requreridas. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. asi->así |
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--- | ||
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# Repeat until the input is correct | ||
# Repite hasta que la entrada sea correcta | ||
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Write a loop which prompts for a number greater than `100`. If the visitor enters another number -- ask them to input again. | ||
Escribe un bucle que solicita un número mayor que `100`. Si el visitante ingresa otro número -- pideles que ingresen un valor de nuevo. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. solicita->solicite |
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The loop must ask for a number until either the visitor enters a number greater than `100` or cancels the input/enters an empty line. | ||
El bucle debe pedir por un número hasta que o el visitante ingrese un número mayor que `100` o cancele la entrada/ingresa un la linea vacía. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. "El bucle debe pedir por un número hasta que el visitante ingrese un número mayor que |
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Here we can assume that the visitor only inputs numbers. There's no need to implement a special handling for a non-numeric input in this task. | ||
Aquí podemos asumir que el visitante solo ingresara números. No hay necesidad de implementar un manejo especial para entradas no numéricas en esta tarea. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. ingresara->ingresará |
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[demo] |
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There are many algorithms for this task. | ||
Hay muchos algoritmos para esta tarea. | ||
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Let's use a nested loop: | ||
Vamos a usar un bucle anidado. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Utilicemos un .. |
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```js | ||
For each i in the interval { | ||
check if i has a divisor from 1..i | ||
if yes => the value is not a prime | ||
if no => the value is a prime, show it | ||
Por cada i en el intervalo { | ||
comprobar si i tiene un divisor en 1..i | ||
si sí => el valor no es un primo | ||
si no => el valor es un primo, enséñalo | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Podria cambiarse "si sí" por "si tiene" para que sea más claro. |
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} | ||
``` | ||
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The code using a label: | ||
El codigo usando una etiqueta: | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. codigo->código |
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```js run | ||
let n = 10; | ||
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nextPrime: | ||
for (let i = 2; i <= n; i++) { // for each i... | ||
for (let i = 2; i <= n; i++) { // por cada i... | ||
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for (let j = 2; j < i; j++) { // look for a divisor.. | ||
if (i % j == 0) continue nextPrime; // not a prime, go next i | ||
for (let j = 2; j < i; j++) { // buscar por un divisor.. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. "buscar un divisor.." |
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if (i % j == 0) continue nextPrime; // no es un primo, ir al proximo i | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Podría eliminarse el "un" |
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} | ||
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alert( i ); // a prime | ||
alert( i ); // un primo | ||
} | ||
``` | ||
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There's a lot of space to opimize it. For instance, we could look for the divisors from `2` to square root of `i`. But anyway, if we want to be really efficient for large intervals, we need to change the approach and rely on advanced maths and complex algorithms like [Quadratic sieve](https://en.wikipedia.org/wiki/Quadratic_sieve), [General number field sieve](https://en.wikipedia.org/wiki/General_number_field_sieve) etc. | ||
Hay un monton de espacio para optimizarlo. Por ejemplo, podriamos buscar por divisores desde `2` hasta la raíz cuadrada de `i`. Pero de todas formas, si queremos ser realmente eficientes para intervalos grandes, tenemos que cambiar el enfoque y confiar en matemáticas avanzadas y algoritmos complejos como [Criba cuadrática](https://es.wikipedia.org/wiki/Criba_cuadr%C3%A1tica), [Criba general del cuerpo de números](https://es.wikipedia.org/wiki/Criba_general_del_cuerpo_de_n%C3%BAmeros) etc. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. "Hay mucho lugar para la mejora. Por ejemplo..." |
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# Output prime numbers | ||
# Muestra números primos | ||
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An integer number greater than `1` is called a [prime](https://en.wikipedia.org/wiki/Prime_number) if it cannot be divided without a remainder by anything except `1` and itself. | ||
Un número entero mayor que `1` es llamado [primo](https://es.wikipedia.org/wiki/N%C3%BAmero_primo) si no puede ser divido sin un residuo por cualquier número excepto `1` y el mismo. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. divido->dividido |
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In other words, `n > 1` is a prime if it can't be evenly divided by anything except `1` and `n`. | ||
En otras palabras, `n > 1` es un primo si no puede ser divido parejamente por cualquier número except `1` y `n`. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. divido parejamente -> dividido exactamente There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. cualquier->ningún |
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For example, `5` is a prime, because it cannot be divided without a remainder by `2`, `3` and `4`. | ||
Por ejemplo, `5` es un primo, porque no puede ser divido sin un residuo por `2`, `3` y `4`. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. "..porque no puede ser divido exactamente por |
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**Write the code which outputs prime numbers in the interval from `2` to `n`.** | ||
**Escribe el código que muestra números primos en el intervalo de `2` a `n`.** | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. muestra->muestre |
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For `n = 10` the result will be `2,3,5,7`. | ||
Para `n = 10` el resultado sera `2, 3, 5, 7`. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. sera->será |
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P.S. The code should work for any `n`, not be hard-tuned for any fixed value. | ||
PD. El código deberia funcionar para cualquier `n`, no debe estar programado para valores fijos. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. deberia ->debería |
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Falta tilde en la U