更新时间:2023-11-24 09:05:46
根据霍华德的建议下,我决定,我不想用任何东西,但基本数组类型。该算法最初我挑是一个痛苦在Java中实现,因此非常感谢死缠烂打的意见,我去的字典下令在Wikipedia 的描述算法。这里是我结束了:
As per Howard's advice, I decided I didn't want to use anything but the primitive array type. The algorithm I initially picked was a pain to implement in Java, so thanks to stalker's advice, I went with the lexicographic-ordered algorithm described at Wikipedia. Here's what I ended up with:
public static int[][] generatePermutations(int N) {
int[][] a = new int[factorial(N)][N];
for (int i = 0; i < N; i++) a[0][i] = i;
for (int i = 1; i < a.length; i++) {
a[i] = Arrays.copyOf(a[i-1], N);
int k, l;
for (k = N - 2; a[i][k] >= a[i][k+1]; k--);
for (l = N - 1; a[i][k] >= a[i][l]; l--);
swap(a[i], k, l);
for (int j = 1; k+j < N-j; j++) swap(a[i], k+j, N-j);
}
return a;
}
private static void swap(int[] is, int k, int l) {
int tmp_k = is[k];
int tmp_l = is[l];
is[k] = tmp_l;
is[l] = tmp_k;
}