27 lines
681 B
PHP
27 lines
681 B
PHP
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<?php
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function abundant($input) {
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$max = floor(sqrt($input));
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$sum = 1;
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for($div=2;$div<=$max ;$div++) {
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if($input % $div == 0) {
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$sum += ($input/$div != $div) ? $input/$div + $div : $div;
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if($sum > $input)
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return true;
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}
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}
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return false;
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}
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//Find all abundant numbers
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for($number = 12; $number <= 28123 ; $number++) {
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if(abundant($number)) { $adjnum[] = $number; }
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}
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$sum = array_sum(range(1,23));
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for($test = 24; $test <= 20162; $test++) {
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$nadundant = true;
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for($index = 0; $adjnum[$index] < $test; $index++) {
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if(abundant($test - $adjnum[$index])) {$nadundant = false; break; }
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}
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if($nadundant) {$sum += $test; }
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}
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echo $sum;
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