PHP Program to Remove Duplicate Characters with Explanation
PHP
Medium
PHP Strings
43 views
1 min read
80 words
This problem helps you practice core PHP fundamentals in a practical way. It builds intuition around remove, duplicate, character. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Remove duplicate characters but keep the first occurrence (spaces included).
Input Format
One line string s.
Output Format
One line result.
Constraints
|s|
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
<?php
$inputText=rtrim(stream_get_contents(STDIN));
if($inputText==='') exit;
$seen=[]; $out='';
for($i=0,$n=strlen($inputText);$i<$n;$i++){
$ch=$inputText[$i];
if(!isset($seen[$ch])){ $seen[$ch]=true; $out.=$ch; }
}
echo $out;
?>
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
Remove duplicate characters but keep the first occurrence (spaces included).
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
$inputText=rtrim(stream_get_contents(STDIN));
if($inputText==='') exit;
$seen=[]; $out='';
for($i=0,$n=strlen($inputText);$i<$n;$i++){
$ch=$inputText[$i];
if(!isset($seen[$ch])){ $seen[$ch]=true; $out.=$ch; }
}
echo $out;
?>
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