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| <?php | |
| // This function takes an array of denominators for a currency and a sum, and returns an array describing the most efficient way to express the sum in terms of denominations. | |
| // E.g. A sum, such as 200 EUR can be expressed in terms of 100x2, which is inefficient, as there is the denomination 200 for this job. | |
| // The function will return the most efficient way to express the sum, not 100x2, but 200x1. | |
| // Recommended to round both, the expected and actual value to 2 decimal places. | |
| // FUNCTION | |
| // getChange function | |
| function getChange($sum, $denominations) { | |
| // Initiate empty results array | |
| $results = []; | |
| rsort($denominations); | |
| foreach ($denominations as $denomination) { | |
| $frequency = (int)(floor(($sum) / $denomination)); | |
| $results[$denomination] = $frequency; | |
| $sum = round($sum - ($denomination * $frequency), 2); | |
| } | |
| return $results; | |
| } | |
| // END FUNCTION | |
| // Currency denominations for sample use and test | |
| $denominations = ['500', '200', '100', '50', '20', '10', '5', '2', '1', '0.50', '0.20', '0.10', '0.05', '0.02', '0.01']; | |
| // BEGIN TEST | |
| // Error counter | |
| $errors = 0; | |
| // Number of iterations | |
| $i = 888.88; | |
| // Expected value is 0.00 from the start | |
| $val_exp = 0.00; | |
| while ($val_exp <= $i) { | |
| // Call getChange function | |
| $results = getChange($val_exp, $denominations); | |
| // Reset calculated value; | |
| $val_is = 0; | |
| // Go through each denomination, add value to calculated total | |
| foreach ($results as $denomination => $frequency) { | |
| if ($frequency) { | |
| $val_is += ($denomination * $frequency); | |
| } | |
| } | |
| // Round both values, expected and actual, to 2 d.p. | |
| $val_exp = round($val_exp, 2); | |
| $val_is = round($val_is, 2); | |
| // Increase error counter if difference detected | |
| if ($val_is != $val_exp) { | |
| $errors += 1; | |
| } | |
| // Increase expected value by 0.01 | |
| $val_exp += 0.01; | |
| } | |
| // Echo number of errors encountered | |
| echo "$errors errors encountered for $i iterations<br><br>"; | |
| // END TEST | |
| // SAMPLE USE | |
| $sum = 372.37; | |
| $results = getChange($sum, $denominations); | |
| echo "Best way to return change for $sum:<br><br>"; | |
| foreach ($results as $denomination => $frequency) { | |
| if ($frequency) { | |
| echo "$frequency times " . round($denomination, 2) . " EUR<br>"; | |
| } | |
| } | |
| // END SAMPLE USE |
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