PHP Program to Multiply Without Star with Explanation
PHP
Hard
PHP Operators
30 views
1 min read
82 words
This problem helps you practice core PHP fundamentals in a practical way. It builds intuition around multiply, one, star. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Multiply a and b using only addition and bit shifts.
Input Format
One line: a b (non-negative).
Output Format
One integer product.
Constraints
0
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;
[$a,$b]=array_map('intval',preg_split('/\\s+/', $inputText));
$res=0;
while($b>0){
if($b&1) $res += $a;
$a <<= 1;
$b >>= 1;
}
echo $res;
?>
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
Multiply a and b using only addition and bit shifts.
Input / Output
Input
One line: a b (non-negative).
Output
One integer product.
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;
[$a,$b]=array_map('intval',preg_split('/\\s+/', $inputText));
$res=0;
while($b>0){
if($b&1) $res += $a;
$a <<= 1;
$b >>= 1;
}
echo $res;
?>
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