基础算法3——直接选择排序和堆排序

public class MySelectionSort {

// 直接选择排序
public void StraightSelectionSort(double[] sorted) {
for (int i = 1; i < sorted.length; i++) {
int minIndex = findMinIndex(sorted, i);
exchange(sorted, i, minIndex);
}
}

private void exchange(double[] sorted, int i, int j) {
// TODO Auto-generated method stub
if (i < sorted.length && j < sorted.length && i < j && i >= 0 && j >= 0) {
double temp = sorted[i];
sorted[i] = sorted[j];
sorted[j] = temp;
}
}

private int findMinIndex(double[] sorted, int i) {
// TODO Auto-generated method stub
int minIndex = 1;
double minValue = Double.MAX_VALUE;
for (int j = i; j < sorted.length; j++) {
if (sorted[j] < minValue) {
minValue = sorted[j];
minIndex = j;
}
}
return minIndex;
}

//小顶堆
public void heapSelectionSort(double[] sorted) {
int sortedLen = sorted.length;

for (int i = sortedLen / 2; i > 0; i--) {
heapAdjust(sorted, i, sortedLen);
}
for (int i = sortedLen; i > 1; --i) {
exchange(sorted, 1, i);
heapAdjust(sorted, 1, i - 1);
}
}

public void heapAdjust(double[] sorted, int start, int end) {
if (start < end) {
double temp = sorted[start];
// 这个地方j<end与课本不同，j<=end会报错：
for (int j = 2 * start; j < end; j *= 2) {
if (j + 1 < end && sorted[j] - sorted[j + 1] > 10e-6) {
++j;
}
if (temp <= sorted[j]) {
break;
}
sorted[start] = sorted[j];
start = j;
}
sorted[start] = temp;
}
}

}