PHP Program to Book Borrowing with Explanation
PHP
Medium
PHP OOP Basics
39 views
1 min read
103 words
This problem helps you practice core PHP fundamentals in a practical way. It builds intuition around book, borrow, line. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Commands: ADD book, BORROW book, RETURN book. Track if a book is available. BORROW unavailable prints FAIL.
Input Format
First line q. Next q lines.
Output Format
Outputs for BORROW.
Constraints
q
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
<?php
class Library{
private $avail=[];
function add($b){ $this->avail[$b]=true; }
function borrow($b){
if(isset($this->avail[$b]) && $this->avail[$b]===true){ $this->avail[$b]=false; return 'OK'; }
return 'FAIL';
}
function ret($b){ if(isset($this->avail[$b])) $this->avail[$b]=true; }
}
$inputLines=preg_split('/\\R/', rtrim(stream_get_contents(STDIN)));
if(!$inputLines || trim($inputLines[0])==='') exit;
$q=intval($inputLines[0]);
$lib=new Library(); $output=[];
for($i=1;$i<=$q;$i++){
$tokens=preg_split('/\\s+/', trim($inputLines[$i] ?? ''), 2);
$cmd=$tokens[0] ?? '';
$arg=$tokens[1] ?? '';
if($cmd==='ADD') $lib->add($arg);
elseif($cmd==='BORROW') $output[]=$lib->borrow($arg);
elseif($cmd==='RETURN') $lib->ret($arg);
}
echo implode(PHP_EOL,$output);
?>
Output Example
Input:
6
ADD Dune
BORROW Dune
BORROW Dune
RETURN Dune
BORROW Dune
BORROW Other
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
Commands: ADD book, BORROW book, RETURN book. Track if a book is available. BORROW unavailable prints FAIL.
Input / Output
Input
First line q. Next q lines.
Output
Outputs for BORROW.
Examples
Input:
6
ADD Dune
BORROW Dune
BORROW Dune
RETURN Dune
BORROW Dune
BORROW Other
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
class Library{
private $avail=[];
function add($b){ $this->avail[$b]=true; }
function borrow($b){
if(isset($this->avail[$b]) && $this->avail[$b]===true){ $this->avail[$b]=false; return 'OK'; }
return 'FAIL';
}
function ret($b){ if(isset($this->avail[$b])) $this->avail[$b]=true; }
}
$inputLines=preg_split('/\\R/', rtrim(stream_get_contents(STDIN)));
if(!$inputLines || trim($inputLines[0])==='') exit;
$q=intval($inputLines[0]);
$lib=new Library(); $output=[];
for($i=1;$i<=$q;$i++){
$tokens=preg_split('/\\s+/', trim($inputLines[$i] ?? ''), 2);
$cmd=$tokens[0] ?? '';
$arg=$tokens[1] ?? '';
if($cmd==='ADD') $lib->add($arg);
elseif($cmd==='BORROW') $output[]=$lib->borrow($arg);
elseif($cmd==='RETURN') $lib->ret($arg);
}
echo implode(PHP_EOL,$output);
?>
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