PHP Program to Rotate Array Right with Explanation
PHP
Medium
PHP Arrays
30 views
1 min read
91 words
This problem helps you practice core PHP fundamentals in a practical way. It builds intuition around rotate, right, position. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Rotate an array to the right by k positions.
Input Format
Line1 n k. Line2 n integers.
Output Format
One line rotated.
Constraints
n
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
<?php
$inputText=trim(stream_get_contents(STDIN));
if($inputText==='') exit;
$tokens=preg_split('/\\s+/', $inputText);
$i=0; $n=intval($tokens[$i++] ?? 0);
$k=intval($tokens[$i++] ?? 0);
$a=[];
for($t=0;$t<$n;$t++) $a[] = $tokens[$i++] ?? '0';
if($n===0){ echo ''; exit; }
$k = $k % $n;
$output=[];
for($t=$n-$k;$t<$n;$t++) $output[]=$a[$t];
for($t=0;$t<$n-$k;$t++) $output[]=$a[$t];
echo implode(' ',$output);
?>
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Solution Guide
Problem
Rotate an array to the right by k positions.
Input / Output
Input
Line1 n k. Line2 n integers.
Details
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Official Solution
<?php
$inputText=trim(stream_get_contents(STDIN));
if($inputText==='') exit;
$tokens=preg_split('/\\s+/', $inputText);
$i=0; $n=intval($tokens[$i++] ?? 0);
$k=intval($tokens[$i++] ?? 0);
$a=[];
for($t=0;$t<$n;$t++) $a[] = $tokens[$i++] ?? '0';
if($n===0){ echo ''; exit; }
$k = $k % $n;
$output=[];
for($t=$n-$k;$t<$n;$t++) $output[]=$a[$t];
for($t=0;$t<$n-$k;$t++) $output[]=$a[$t];
echo implode(' ',$output);
?>
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