library/Permutation.java

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• Last update: 2023-03-23 19:06:36+09:00

Depends on

• library/FastIO.java

Verified with

• library/Permutation_test.java

Code

package library;

import java.util.*;
import library.FastIO;

class Permutation implements Iterator<int[]>, Iterable<int[]> { // N=next.length
	private int next[];

	// O(N)
	public Permutation(int n) {
		FastIO.nonNegativeCheck(n);
		next = new int[n];
		for(int i = 0; i < n; i ++) next[i] = i;
	}
	public Permutation(int[] a) {
		next = a.clone();
	}

	@Override
	public final boolean hasNext() { return next != null; } // O(1)

	@Override
	public final int[] next() { // O(1)
		int[] r = next.clone();
		next = nextPermutation(next);
		return r;
	}

	@Override
	public final Iterator<int[]> iterator() { return this; } // O(1)

	public final int[] nextPermutation(int[] a) { // O(N)
		if(a == null || a.length < 2) return null;
		int p = 0;
		for(int i = a.length - 2; i >= 0; i --) {
			if(a[i] >= a[i + 1]) continue;
			p = i;
			break;
		}
		int q = 0;
		for(int i = a.length - 1; i > p; i --) {
			if(a[i] <= a[p]) continue;
			q = i;
			break;
		}
		if(p == 0 && q == 0) return null;
		swap(a, p, q);
		int l = p;
		int r = a.length;
		while(++ l < -- r) swap(a, l, r);
		return a;
	}

	private static final void swap(int[] a, int l, int r) {
		int tmp = a[l];
		a[l] = a[r];
		a[r] = tmp;
	}
}

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.11.2/x64/lib/python3.11/site-packages/onlinejudge_verify/documentation/build.py", line 71, in _render_source_code_stat
    bundled_code = language.bundle(stat.path, basedir=basedir, options={'include_paths': [basedir]}).decode()
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.2/x64/lib/python3.11/site-packages/onlinejudge_verify/languages/user_defined.py", line 71, in bundle
    return subprocess.check_output(shlex.split(command))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.2/x64/lib/python3.11/subprocess.py", line 466, in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.2/x64/lib/python3.11/subprocess.py", line 571, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['false']' returned non-zero exit status 1.

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