import java.util.Arrays;
//好吧！这是一个排序的问题，有点复杂，
//另外友好提示：技术不行的就别看了。
public class ArrayUtils{
public static void main(String[] args) {
int[] arr={1,3,2,5,6,4};
sort(arr);
System.out.println(Arrays.toString(arr));
}
private static final int MAX_RUN_COUNT = 67;
private static final int MAX_RUN_LENGTH = 33;
private static final int QUICKSORT_THRESHOLD = 286;
private static final int INSERTION_SORT_THRESHOLD = 47;
//高手请把这个排序的思路讲明白！！包括这些常量为什么这么定义？？
public static void sort(int[] a) {
sort(a, 0, a.length - 1);
}
public static void sort(int[] a, int left, int right) {
if (right - left < QUICKSORT_THRESHOLD) {
sort(a, left, right, true);
return;
}
int[] run = new int[MAX_RUN_COUNT + 1];
int count = 0; run[0] = left;
for (int k = left; k < right; run[count] = k) {
if (a[k] < a[k + 1]) { // ascending
while (++k <= right && a[k - 1] <= a[k]);
} else if (a[k] > a[k + 1]) { // descending
while (++k <= right && a[k - 1] >= a[k]);
for (int lo = run[count] - 1, hi = k; ++lo < --hi; ) {
int t = a[lo]; a[lo] = a[hi]; a[hi] = t;
}
} else { // equal
for (int m = MAX_RUN_LENGTH; ++k <= right && a[k - 1] == a[k]; ) {
if (--m == 0) {
sort(a, left, right, true);
return;
}
}
}
if (++count == MAX_RUN_COUNT) {
sort(a, left, right, true);
return;
}
}
if (run[count] == right++) {
run[++count] = right;
} else if (count == 1) {
return;
}
int[] b; byte odd = 0;
for (int n = 1; (n <<= 1) < count; odd ^= 1);
if (odd == 0) {
b = a; a = new int[b.length];
for (int i = left - 1; ++i < right; a = b);
} else {
b = new int[a.length];
}
for (int last; count > 1; count = last) {
for (int k = (last = 0) + 2; k <= count; k += 2) {
int hi = run[k], mi = run[k - 1];
for (int i = run[k - 2], p = i, q = mi; i < hi; ++i) {
if (q >= hi || p < mi && a[p] <= a[q]) {
b = a[p++];
} else {
b = a[q++];
}
}
run[++last] = hi;
}
if ((count & 1) != 0) {
for (int i = right, lo = run[count - 1]; --i >= lo;
b = a
);
run[++last] = right;
}
int[] t = a; a = b; b = t;
}
}
private static void sort(int[] a, int left, int right, boolean leftmost) {
int length = right - left + 1;
if (length < INSERTION_SORT_THRESHOLD) {
if (leftmost) {
for (int i = left, j = i; i < right; j = ++i) {
int ai = a[i + 1];
while (ai < a[j]) {
a[j + 1] = a[j];
if (j-- == left) {
break;
}
}
a[j + 1] = ai;
}
} else {
do {
if (left >= right) {
return;
}
} while (a[++left] >= a[left - 1]);
for (int k = left; ++left <= right; k = ++left) {
int a1 = a[k], a2 = a[left];
if (a1 < a2) {
a2 = a1; a1 = a[left];
}
while (a1 < a[--k]) {
a[k + 2] = a[k];
}
a[++k + 1] = a1;
while (a2 < a[--k]) {
a[k + 1] = a[k];
}
a[k + 1] = a2;
}
int last = a[right];
while (last < a[--right]) {
a[right + 1] = a[right];
}
a[right + 1] = last;
}
return;
}
int seventh = (length >> 3) + (length >> 6) + 1;
int e3 = (left + right) >>> 1; // The midpoint
int e2 = e3 - seventh;
int e1 = e2 - seventh;
int e4 = e3 + seventh;
int e5 = e4 + seventh;
if (a[e2] < a[e1]) { int t = a[e2]; a[e2] = a[e1]; a[e1] = t; }
if (a[e3] < a[e2]) { int t = a[e3]; a[e3] = a[e2]; a[e2] = t;
if (t < a[e1]) { a[e2] = a[e1]; a[e1] = t; }
}
if (a[e4] < a[e3]) { int t = a[e4]; a[e4] = a[e3]; a[e3] = t;
if (t < a[e2]) { a[e3] = a[e2]; a[e2] = t;
if (t < a[e1]) { a[e2] = a[e1]; a[e1] = t; }
}
}
if (a[e5] < a[e4]) { int t = a[e5]; a[e5] = a[e4]; a[e4] = t;
if (t < a[e3]) { a[e4] = a[e3]; a[e3] = t;
if (t < a[e2]) { a[e3] = a[e2]; a[e2] = t;
if (t < a[e1]) { a[e2] = a[e1]; a[e1] = t; }
}
}
}
int less = left;
int great = right;
if (a[e1] != a[e2] && a[e2] != a[e3] && a[e3] != a[e4] && a[e4] != a[e5]) {
int pivot1 = a[e2];
int pivot2 = a[e4];
a[e2] = a[left];
a[e4] = a[right];
while (a[++less] < pivot1);
while (a[--great] > pivot2);
outer:
for (int k = less - 1; ++k <= great; ) {
int ak = a[k];
if (ak < pivot1) {
a[k] = a[less];
a[less] = ak;
++less;
} else if (ak > pivot2) {
while (a[great] > pivot2) {
if (great-- == k) {
break outer;
}
}
if (a[great] < pivot1) {
a[k] = a[less];
a[less] = a[great];
++less;
} else {
a[k] = a[great];
}
a[great] = ak;
--great;
}
}
a[left] = a[less - 1]; a[less - 1] = pivot1;
a[right] = a[great + 1]; a[great + 1] = pivot2;
sort(a, left, less - 2, leftmost);
sort(a, great + 2, right, false);
if (less < e1 && e5 < great) {
while (a[less] == pivot1) {
++less;
}
while (a[great] == pivot2) {
--great;
}
outer:
for (int k = less - 1; ++k <= great; ) {
int ak = a[k];
if (ak == pivot1) {
a[k] = a[less];
a[less] = ak;
++less;
} else if (ak == pivot2) {
while (a[great] == pivot2) {
if (great-- == k) {
break outer;
}
}
if (a[great] == pivot1) {
a[k] = a[less];
a[less] = pivot1;
++less;
} else {
a[k] = a[great];
}
a[great] = ak;
--great;
}
}
}
sort(a, less, great, false);
} else {
int pivot = a[e3];
for (int k = less; k <= great; ++k) {
if (a[k] == pivot) {
continue;
}
int ak = a[k];
if (ak < pivot) {
a[k] = a[less];
a[less] = ak;
++less;
} else {
while (a[great] > pivot) {
--great;
}
if (a[great] < pivot) {
a[k] = a[less];
a[less] = a[great];
++less;
} else {
a[k] = pivot;
}
a[great] = ak;
--great;
}
}
sort(a, left, less - 1, leftmost);
sort(a, great + 1, right, false);
}
}
}
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