假如做个XX网， 当然要为金牌会员提供最优秀的资源（people）服务。
优秀资源比较规则是：
1. 有籍贯（籍贯莫有的， 不敢要）
2. 钱多
3. 籍贯为'jx'的优先， 其他...
下面程序就是求最优资源实现：
package algorithm.max;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Comparator;
import java.util.PriorityQueue;
/**
* max n algorithm
*
* @author yangwm Oct 23, 2010 11:36:54 PM
*/
public class MaxNAlgorithm<E> {
/**
* max + n + comparator
*
* @param <E>
* @param input
* @param n
* @param comparator
* @return
*/
public static <E> E[] max(E[] input, int n, Comparator<? super E> comparator) {
PriorityQueue<E> priorityQueue = new PriorityQueue<E>(n, comparator);
for (int i = 0; i < input.length; i++) {
priorityQueue.add(input[i]);
if (i >= n) {
priorityQueue.poll();
}
}
E[] result = newGenericArray(input[0], priorityQueue.size());
for (int i = result.length - 1; i >= 0; i--) {
result[i] = priorityQueue.poll();
}
return result;
}
/**
* max + n
*
* @param <E>
* @param input
* @param n
* @return
*/
public static <E> E[] max(E[] input, int n) {
PriorityQueue<E> priorityQueue = new PriorityQueue<E>(n);
for (int i = 0; i < input.length; i++) {
priorityQueue.add(input[i]);
if (i >= n) {
priorityQueue.poll();
}
}
E[] result = newGenericArray(input[0], priorityQueue.size());
for (int i = result.length - 1; i >= 0; i--) {
result[i] = priorityQueue.poll();
}
return result;
}
@SuppressWarnings("unchecked")
static <E> E[] newGenericArray(E e, int size) {
Class<E> type = (Class<E>) e.getClass();
return (E[]) Array.newInstance(type, size);
}
/**
* @param args
*/
public static void main(String[] args) {
Integer[] input = new Integer[] { 2, 7, 6, 8, 9, 18, 11, 5, 3, 20 };
int n = 3;
System.out.println("------MaxNAlgorithm Array max n-------");
Integer[] result = max(input, n);
System.out.println(Arrays.toString(result));
}
}
/*
------MaxNAlgorithm Array max n-------
[20, 18, 11]
*/
/**
*
*/
package algorithm.max;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Random;
/**
* max n algorithm beanch2
*
* @author yangwm Oct 23, 2010 11:58:58 PM
*/
public class MaxNAlgorithmBeanch2 {
/**
* @param args
*/
public static void main(String[] args) {
/*
*
*/
int inputTotal = 1000000;
int n = 100;
/*
* test data
*/
List<People> inputList = new ArrayList<People>(inputTotal);
for (int i = 0; i < inputTotal; i++) {
People people = null;
int money = i / 10;
int factor = new Random().nextInt(5) + 1;
if (factor == 1) {
people = new People(i, "jx", money);
} else if (factor == 2) {
people = new People(i, "bj", money);
} else if (factor == 3) {
people = new People(i, "sh", money);
} else {
people = new People(i, null, money);
}
inputList.add(people);
}
Collections.shuffle(inputList);
System.out.println("test begin inputTotal: " + inputTotal + ", n: " + n);
System.out.println("test data inputList.size(): " + inputList.size());
//-----------------------------------------------------------------
People[] inputArray = new People[inputList.size()];
for (int i = 0; i < inputArray.length; i++) {
inputArray[i] = inputList.get(i);
}
System.out.println("-------JDK Arrays.sort max n with Comparable-------");
/*
* max and test print
*/
long begin = System.currentTimeMillis();
Arrays.sort(inputArray);
People[] resultArray = (People[]) Array.newInstance(People.class, n);
for (int i = inputArray.length - 1, resultIdx = 0; i >= inputArray.length - n; i--) {
resultArray[resultIdx++] = inputArray[i];
}
long end = System.currentTimeMillis();
System.out.println("cosume: " + (end - begin) + " ms");
System.out.println("resultArray.length: " + resultArray.length);
System.out.println("resultArray of first ten : " + Arrays.toString(Arrays.copyOf(resultArray, 10)));
//-----------------------------------------------------------------
inputArray = new People[inputList.size()];
for (int i = 0; i < inputArray.length; i++) {
inputArray[i] = inputList.get(i);
}
System.out.println("-------MaxNAlgorithm Array max n with Comparable-------");
/*
* max and test print
*/
begin = System.currentTimeMillis();
resultArray = MaxNAlgorithm.<People>max(inputArray, n);
end = System.currentTimeMillis();
System.out.println("cosume: " + (end - begin) + " ms");
System.out.println("resultArray.length: " + resultArray.length);
System.out.println("resultArray of first ten : " + Arrays.toString(Arrays.copyOf(resultArray, 10)));
}
/**
* test object for max n algorithm beanch
*
* @author yangwm Oct 24, 2010 4:16:58 PM
*/
static class People implements Comparable<People> {
public int id;
public String province;
public int money;
public People(int id, String province, int money) {
this.id = id;
this.province = province;
this.money = money;
}
@Override
public int compareTo(People o) {
if (province != null && o.province == null) {
return 1;
} else if (province == null && o.province != null) {
return -1;
} else {
if (money > o.money) {
return 1;
} else if (money < o.money) {
return -1;
} else {
if (province == null && o.province == null) {
return 0;
} if (province.equalsIgnoreCase("jx")) {
return 1;
} else if (o.province.equalsIgnoreCase("jx")) {
return -1;
} else {
return province.compareToIgnoreCase(o.province);
}
}
}
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("id=");
sb.append(id);
sb.append(" province=");
sb.append(province);
sb.append(" money=");
sb.append(money);
return sb.toString();
}
}
}
/*
test begin inputTotal: 1000000, n: 100
test data inputList.size(): 1000000
-------JDK Arrays.sort max n with Comparable-------
cosume: 1218 ms
resultArray.length: 100
resultArray of first ten : [id=999997 province=jx money=99999, id=999993 province=jx money=99999, id=999992 province=sh money=99999, id=999996 province=sh money=99999, id=999991 province=bj money=99999, id=999990 province=bj money=99999, id=999995 province=bj money=99999, id=999989 province=jx money=99998, id=999980 province=bj money=99998, id=999987 province=bj money=99998]
-------MaxNAlgorithm Array max n with Comparable-------
cosume: 578 ms
resultArray.length: 100
resultArray of first ten : [id=999997 province=jx money=99999, id=999993 province=jx money=99999, id=999996 province=sh money=99999, id=999992 province=sh money=99999, id=999990 province=bj money=99999, id=999991 province=bj money=99999, id=999995 province=bj money=99999, id=999989 province=jx money=99998, id=999985 province=bj money=99998, id=999980 province=bj money=99998]
*/
/**
*
*/
package algorithm.max;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Random;
/**
* max n algorithm beanch3
*
* @author yangwm Oct 24, 2010 4:16:12 PM
*/
public class MaxNAlgorithmBeanch3 {
/**
* @param args
*/
public static void main(String[] args) {
/*
*
*/
int inputTotal = 1000000;
int n = 100;
/*
* test data
*/
List<People> inputList = new ArrayList<People>(inputTotal);
for (int i = 0; i < inputTotal; i++) {
People people = null;
int money = i / 10;
int factor = new Random().nextInt(5) + 1;
if (factor == 1) {
people = new People(i, "jx", money);
} else if (factor == 2) {
people = new People(i, "bj", money);
} else if (factor == 3) {
people = new People(i, "sh", money);
} else {
people = new People(i, null, money);
}
inputList.add(people);
}
Collections.shuffle(inputList);
System.out.println("test begin inputTotal: " + inputTotal + ", n: " + n);
System.out.println("test data inputList.size(): " + inputList.size());
//-----------------------------------------------------------------
People[] inputArray = new People[inputList.size()];
for (int i = 0; i < inputArray.length; i++) {
inputArray[i] = inputList.get(i);
}
System.out.println("-------JDK Arrays.sort max n with Comparable-------");
/*
* max and test print
*/
long begin = System.currentTimeMillis();
Arrays.sort(inputArray, new PeopleComparator());
People[] resultArray = (People[]) Array.newInstance(People.class, n);
for (int i = inputArray.length - 1, resultIdx = 0; i >= inputArray.length - n; i--) {
resultArray[resultIdx++] = inputArray[i];
}
long end = System.currentTimeMillis();
System.out.println("cosume: " + (end - begin) + " ms");
System.out.println("resultArray.length: " + resultArray.length);
System.out.println("resultArray of first ten : " + Arrays.toString(Arrays.copyOf(resultArray, 10)));
//-----------------------------------------------------------------
inputArray = new People[inputList.size()];
for (int i = 0; i < inputArray.length; i++) {
inputArray[i] = inputList.get(i);
}
System.out.println("-------MaxNAlgorithm Array max n with Comparable-------");
/*
* max and test print
*/
begin = System.currentTimeMillis();
resultArray = MaxNAlgorithm.<People>max(inputArray, n, new PeopleComparator());
end = System.currentTimeMillis();
System.out.println("cosume: " + (end - begin) + " ms");
System.out.println("resultArray.length: " + resultArray.length);
System.out.println("resultArray of first ten : " + Arrays.toString(Arrays.copyOf(resultArray, 10)));
}
/**
* test object for max n algorithm beanch
*
* @author yangwm Oct 24, 2010 4:16:58 PM
*/
static class People {
public int id;
public String province;
public int money;
public People(int id, String province, int money) {
this.id = id;
this.province = province;
this.money = money;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("id=");
sb.append(id);
sb.append(" province=");
sb.append(province);
sb.append(" money=");
sb.append(money);
return sb.toString();
}
}
static class PeopleComparator implements Comparator<People> {
@Override
public int compare(People o1, People o2) {
if (o1 != null && o2.province == null) {
return 1;
} else if (o1.province == null && o2.province != null) {
return -1;
} else {
if (o1.money > o2.money) {
return 1;
} else if (o1.money < o2.money) {
return -1;
} else {
if (o1.province == null && o2.province == null) {
return 0;
} else if (o1.province.equalsIgnoreCase("jx")) {
return 1;
} else if (o2.province.equalsIgnoreCase("jx")) {
return -1;
} else {
return o1.province.compareToIgnoreCase(o2.province);
}
}
}
}
}
}
/*
test begin inputTotal: 1000000, n: 100
test data inputList.size(): 1000000
-------JDK Arrays.sort max n with Comparable-------
cosume: 1078 ms
resultArray.length: 100
resultArray of first ten : [id=999990 province=jx money=99999, id=999993 province=jx money=99999, id=999991 province=sh money=99999, id=999999 province=sh money=99999, id=999982 province=jx money=99998, id=999984 province=jx money=99998, id=999981 province=sh money=99998, id=999989 province=sh money=99998, id=999988 province=bj money=99998, id=999983 province=bj money=99998]
-------MaxNAlgorithm Array max n with Comparable-------
cosume: 547 ms
resultArray.length: 100
resultArray of first ten : [id=999990 province=jx money=99999, id=999993 province=jx money=99999, id=999991 province=sh money=99999, id=999999 province=sh money=99999, id=999984 province=jx money=99998, id=999982 province=jx money=99998, id=999981 province=sh money=99998, id=999989 province=sh money=99998, id=999980 province=bj money=99998, id=999988 province=bj money=99998]
*/