PHP algorithm exercise 6: Determine whether a value appears three consecutive times in the array

In "PHP Algorithm Exercise 5: Determining whether a number is a multiple of a specified number", we introduce to you how to determine whether a number is a multiple of a specified number. This is a very simple and basic exercise. , everyone must have mastered it.

Now I will continue to teach you about PHP algorithm related knowledge, I hope it can be helpful to everyone!

As the title says, in this article we ask to use PHP to determine whether a value appears three times in an array in a row. That is to say, a value in an array that appears once or twice in a row will be judged as false.

You can practice it locally, and then look at my method below:

The PHP code is as follows:

<?php

function test($nums)
{
    $arra_len = sizeof($nums) - 1;
    $n = 0;
    for ($i = 0; $i < $arra_len; $i++)
    {
        $n = $nums[$i];
        if ($n == $nums[$i + 1] && $n == $nums[$i + 2]) return true;
    }
    return false;
}

var_dump(test(array(1, 1, 2, 2, 1)));
var_dump(test(array(1, 1, 2, 1, 2, 3)));
var_dump(test(array(1, 1, 1, 2, 2, 2, 1)));

The output result is:

Obviously only the third array meets the requirements.

Here you need to understand a sizeof() function; the

sizeof() function is used to calculate the number of units in an array or the number of objects in an object. The number of attributes, the sizeof() function is also an alias of the count() function, and the count() function is also used to return the number of elements in the array.

sizeof The syntax of the function is sizeof(array,mode);,

parameters respectively represent:

array is required and specifies the array.
mode is optional and specifies the mode.
Possible values ​​are:
0 - Default. Do not count all elements in a multidimensional array
1 - Recursively count the number of elements in the array (count all elements in a multidimensional array)

Note: When the variable is not set, or The variable contains an empty array, and the function will return 0; you can use the isset() variable to test whether the variable is set.

→ The isset() function is used to detect whether a variable has been set and is not NULL. If a variable has been released using unset(), then isset() will return FALSE. If you use isset() to test a variable that is set to NULL, it will return FALSE.

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