Java 归并排序算法

/**
*
* 改进后的归并排序:
*
*/
public class ImprovedMergeSort {

private static final int THRESHOLD = 10;

public void sort(int[] data) {
int[] temp = new int[data.length];
mergeSort(data, temp, 0, data.length - 1);
}

private void mergeSort(int[] data, int[] temp, int l, int r) {
int i, j, k;
int mid = (l + r) / 2;
if (l == r)
return;
if ((mid - l) >= THRESHOLD)
mergeSort(data, temp, l, mid);
else
insertSort(data, l, mid - l + 1);
if ((r - mid) > THRESHOLD)
mergeSort(data, temp, mid + 1, r);
else
insertSort(data, mid + 1, r - mid);

for (i = l; i <= mid; i++) {
temp[i] = data[i];
}
for (j = 1; j <= r - mid; j++) {
temp[r - j + 1] = data[j + mid];
}
int a = temp[l];
int b = temp[r];
for (i = l, j = r, k = l; k <= r; k++) {
if (a < b) {
data[k] = temp[i++];
a = temp[i];
} else {
data[k] = temp[j--];
b = temp[j];
}
}
}

/**
* @param data
* @param start
* @param len
*/
private void insertSort(int[] data, int start, int len) {
for (int i = start + 1; i < start + len; i++) {
for (int j = i; (j > start) && data[j] < data[j - 1]; j--) {
swap(data, j, j - 1);
}
}
}

private void swap(int[] data, int i, int j) {
int temp = data[i];
data[i] = data[j];
data[j] = temp;
}

}

Java代码 收藏代码
/**
* 归并排序:
*
*/
public class MergeSort{

public void sort(int[] data) {
int[] temp = new int[data.length];
mergeSort(data, temp, 0, data.length - 1);
}

private void mergeSort(int[] data, int[] temp, int l, int r) {
int mid = (l + r) / 2;
if (l == r)
return;
mergeSort(data, temp, l, mid);
mergeSort(data, temp, mid + 1, r);
for (int i = l; i <= r; i++) {
temp[i] = data[i];
}
int i1 = l;
int i2 = mid + 1;
for (int cur = l; cur <= r; cur++) {
if (i1 == mid + 1)
data[cur] = temp[i2++];
else if (i2 > r)
data[cur] = temp[i1++];
else if (temp[i1] < temp[i2])
data[cur] = temp[i1++];
else
data[cur] = temp[i2++];
}
}
}