Fraction reduction: Difference between revisions
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Took 42.251172302s
</pre>
=={{header|Groovy}}==
{{trans|Java}}
<lang groovy>class FractionReduction {
static void main(String[] args) {
for (int size = 2; size <= 5; size++) {
reduce(size)
}
}
private static void reduce(int numDigits) {
System.out.printf("Fractions with digits of length %d where cancellation is valid. Examples:%n", numDigits)
// Generate allowed numerator's and denominator's
int min = (int) Math.pow(10, numDigits - 1)
int max = (int) Math.pow(10, numDigits) - 1
List<Integer> values = new ArrayList<>()
for (int number = min; number <= max; number++) {
if (isValid(number)) {
values.add(number)
}
}
Map<Integer, Integer> cancelCount = new HashMap<>()
int size = values.size()
int solutions = 0
for (int nIndex = 0; nIndex < size - 1; nIndex++) {
int numerator = values.get(nIndex)
// Must be proper fraction
for (int dIndex = nIndex + 1; dIndex < size; dIndex++) {
int denominator = values.get(dIndex)
for (int commonDigit : digitsInCommon(numerator, denominator)) {
int numRemoved = removeDigit(numerator, commonDigit)
int denRemoved = removeDigit(denominator, commonDigit)
if (numerator * denRemoved == denominator * numRemoved) {
solutions++
cancelCount.merge(commonDigit, 1, { v1, v2 -> v1 + v2 })
if (solutions <= 12) {
println(" When $commonDigit is removed, $numerator/$denominator = $numRemoved/$denRemoved")
}
}
}
}
}
println("Number of fractions where cancellation is valid = $solutions.")
List<Integer> sorted = new ArrayList<>(cancelCount.keySet())
Collections.sort(sorted)
for (int removed : sorted) {
println(" The digit $removed was removed ${cancelCount.get(removed)} times.")
}
println()
}
private static int[] powers = [1, 10, 100, 1000, 10000, 100000]
// Remove the specified digit.
private static int removeDigit(int n, int removed) {
int m = 0
int pow = 0
while (n > 0) {
int r = n % 10
if (r != removed) {
m = m + r * powers[pow]
pow++
}
n /= 10
}
return m
}
// Assumes no duplicate digits individually in n1 or n2 - part of task
private static List<Integer> digitsInCommon(int n1, int n2) {
int[] count = new int[10]
List<Integer> common = new ArrayList<>()
while (n1 > 0) {
int r = n1 % 10
count[r] += 1
n1 /= 10
}
while (n2 > 0) {
int r = n2 % 10
if (count[r] > 0) {
common.add(r)
}
n2 /= 10
}
return common
}
// No repeating digits, no digit is zero.
private static boolean isValid(int num) {
int[] count = new int[10]
while (num > 0) {
int r = num % 10
if (r == 0 || count[r] == 1) {
return false
}
count[r] = 1
num /= 10
}
return true
}
}</lang>
=={{header|Haskell}}==
<lang haskell>import Control.Monad (guard)
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