pc/src/Chapter8/Queue.java at master · rvprg/pc · GitHub

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importstaticjava.util.Arrays.stream;
importstaticjava.util.stream.Collectors.toList;

importjava.io.BufferedReader;
importjava.io.IOException;
importjava.io.InputStreamReader;
importjava.util.List;
importjava.util.stream.LongStream;

publicclassQueue {
privatestaticfinalBufferedReaderreader = newBufferedReader(
newInputStreamReader(System.in));

privatefinalintn;
privatefinalintk;
privatefinalint[] buckets;
privatefinalint[] queue;
privatefinalint[] values;
privatefinalboolean[] skip;
privatelongtotal;
privatelongcounter;

privatestaticfinallong[] factorial = LongStream.rangeClosed(0, 13)
 .map(f -> f == 0 ? 1
 : LongStream.rangeClosed(1, f).reduce(1L,
 (x, y) -> x * y))
 .toArray();

privatestaticfinalLong[][][] cache = newLong[13 + 1][13 + 1][13 + 1];

publicQueue(intn, intl, intr) {
this.n = n;
this.k = l - 1;
buckets = newint[n + 1];
skip = newboolean[n + 1];
queue = newint[l + r - 2];
values = newint[n - (l + r - 2) - 1 < 0 ? 0 : n - (l + r - 2) - 1];
skip[n] = true;
if (cache[n][l][r] != null) {
total = cache[n][l][r];
 } else {
select(0);
cache[n][l][r] = total;
 }
 }

privatevoidselect(intpos) {
if (pos == queue.length) {
for (inti = 1, j = 0; i <= n; ++i) {
if (!skip[i]) {
values[j++] = i;
 }
 }
counter = 0;
count(0);
intnn = queue.length;
total += counter * factorial[nn] /
 (factorial[k] * factorial[nn - k]);
return;
 }

intstart = pos - 1 >= 0 ? queue[pos - 1] + 1 : 1;
for (inti = start; i < n; ++i) {
queue[pos] = i;
skip[i] = true;
select(pos + 1);
skip[i] = false;
 }
 }

privatevoidcount(intpos) {
if (pos == values.length) {
longpermutations = 1;
for (inti = 0; i < buckets.length; ++i) {
permutations *= factorial[buckets[i]];
 }
counter += permutations;
return;
 }

for (intbucket : queue) {
if (bucket > values[pos]) {
buckets[bucket]++;
count(pos + 1);
buckets[bucket]--;
 }
 }
 }

publicstaticvoidmain(String[] args) throwsIOException {
intn = Integer.parseInt(reader.readLine().trim());
for (inti = 0; i < n; ++i) {
List<Integer> line = stream(reader.readLine().split(" "))
 .filter(x -> !x.equals(""))
 .map(Integer::parseInt)
 .collect(toList());
intl = line.get(1);
intr = line.get(2);
if (l + r - 1 > 13) {
System.out.println(0);
 } else {
Queueq = newQueue(line.get(0), l, r);
System.out.println(q.total);
 }
 }
 }

}