思路：在所有算法中只有堆排序和归并排序能够达到时间复杂度的要求，而堆排序对空间的要求又要优于归并排序，所以最后采用了堆排序来实现。

/*构建员工模型*/
class Staff{
int id;//员工id
Staff(int id ){
this.id=id;
}
public void setId(int id){
this.id=id;
}
public int getId(){
return this.id;
}

}
public class StaffSort {
private Staff[] log; // 记录员工序号序列
private int totalStaff; // 员工总人数
private int currentStaff; //此时员工人数

public StaffSort(int totalStaff) {
// TODO Auto-generated constructor stub
this.totalStaff=totalStaff;
currentStaff=0;
log=new Staff[totalStaff];
}

/*
* @author Sam
* @param id
* @return isSuccess
* Described 员工签到*/
public boolean check(int id) {
Staff newStaff = new Staff(id);
log[currentStaff] = newStaff;
trickleUp(currentStaff++);
return true;
}

/*
* @author Sam
* @param index
* @return isSuccess
* Described 向上调整堆模型，使各点的值不大于其双亲结点的值*/
public void trickleUp(int index) {
int parent = (index - 1) / 2;
Staff bottom = log[index];

while (index > 0 && log[parent].getId() < bottom.getId()) {
log[index] = log[parent];
index = parent;
parent = (parent - 1) / 2;
}
log[index] = bottom;
}

/*
* @author Sam
* @param
* @return root
* Described 获取并删除堆顶*/
public Staff remove() {
Staff root = log[0];
log[0] = log[--currentStaff];
trickleDown(0);
return root;
}

/*
* @author Sam
* @param index
* @return
* Described 向下调整堆结构，是堆顶元素不小于孩子结点的值*/
public void trickleDown(int index) {
int largeChild;
Staff top = log[index];
while (index < currentStaff / 2) {
int leftChild = 2 * index + 1;
int rightChild = leftChild + 1;

if (rightChild < currentStaff
&& log[leftChild].getId() < log[rightChild]
.getId()) {
largeChild = rightChild;
} else {
largeChild = leftChild;
}

if (top.getId() >= log[largeChild].getId()) {
break;
}

log[index] = log[largeChild];
index = largeChild;
}
log[index] = top;
}

/*
* @author Sam
* @param args
* @return
* Described 打印排序后的结果*/
public static void main(String[]args){
int[] staffs=new int[]{1,3,5,2,12,10,15};
StaffSort ss=new StaffSort(50);
for(int i=0;i<staffs.length;i++){
ss.check(staffs[i]);
}
while (ss.currentStaff!=0) {
System.out.print(ss.remove().getId()+" ");

}
}

}