Missing Number 1..N

Missing Number 1..N

Medium PHP PHP Arrays 25 views
Explanation Complexity

Problem Statement

You get n-1 numbers from 1..n. Find the missing number.

Input Format

Line1 n. Line2 n-1 integers.

Output Format

One integer missing.

Example

5
1 2 4 5
3

Constraints

n

Input / Output Format

Input Format
Line1 n. Line2 n-1 integers.
Output Format
One integer missing.
Constraints
n

Examples

Input:
5 1 2 4 5
Output:
3

Example Solution (Public)

PHP 
<?php
$inputText=trim(stream_get_contents(STDIN));
if($inputText==='') exit;
$tokens=preg_split('/\\s+/', $inputText);
$i=0; $n=intval($tokens[$i++] ?? 0);
$sum=intdiv($n*($n+1),2);
for($k=0;$k<$n-1;$k++) $sum -= intval($tokens[$i++] ?? 0);
echo $sum;
?>

Official Solution Code

<?php
$inputText=trim(stream_get_contents(STDIN));
if($inputText==='') exit;
$tokens=preg_split('/\\s+/', $inputText);
$i=0; $n=intval($tokens[$i++] ?? 0);
$sum=intdiv($n*($n+1),2);
for($k=0;$k<$n-1;$k++) $sum -= intval($tokens[$i++] ?? 0);
echo $sum;
?>
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