腾讯面试题：一亿数字获取前100个最大的数字办法

比较笨的办法。效率有点低。 只是实现了功能。 期待牛人的算法。

我弄了个最佳方案 http://blog.csdn.net/yjflinchong/article/details/7533972 3秒就搞定了

一亿数字获取前100个最大的数字 这个方案需要700秒

///http://blog.csdn.net/yjflinchong/article/details/7532018

package com.my.util;

import java.io.*;

import java.util.*;

import java.net.*;

public class WebTest {

public static int last = 333333333;

public static int max = 100000000;//数据总数

public static int sp = 1000000;//分割数据条数

public static int[] ary = new int[100];

public static void main(String[] args) {

splitFile();

Date d1 = new Date();

find("d:/file/file.txt");

System.out.println(Arrays.toString(ary)+"========");

Date d2 = new Date();

System.out.println(d2.getTime()-d1.getTime());

}

public static void splitFile(){

StringBuffer str = new StringBuffer("");

int num = 1;

for (int i = 1; i < (max+1); i++) {

str.append(i+"\t\n");

if(i%1000000==0){

appendToFile("d:/file/file.txt", str.toString());

str = new StringBuffer("");

num++;

}

}

appendToFile("d:/file/file.txt", last+"");

}

public static void appendToFile(String file,String text){

try

{

FileWriter fw =new FileWriter(file,true);

BufferedWriter bw=new BufferedWriter(fw);

bw.write(text);

bw.flush();

}catch (Exception e) {

}

}

public static String readFile(String path){

StringBuffer str = new StringBuffer("");

try {

String line = null;

BufferedReader reader = new BufferedReader(new FileReader(path));

while ((line = reader.readLine()) != null) {

str.append(line);

}

reader.close();

} catch (Exception e) {

e.printStackTrace();

}

return str.toString();

}

public static void find(int[] bak){

for (int i = 0; i < bak.length; i++) {

ary[0] = bak[i];

sort(ary);

}

}///http://blog.csdn.net/yjflinchong/article/details/7532018

public static void find(String path){

try {///http://blog.csdn.net/yjflinchong/

String line = null;

BufferedReader reader = new BufferedReader(new FileReader(path));

while ((line = reader.readLine()) != null) {

ary[0] = Integer.parseInt(line.trim());

sort(ary);

}

reader.close();

} catch (Exception e) {

e.printStackTrace();

}

}

///http://blog.csdn.net/yjflinchong/article/details/7532018

public static void sort(int[] array){

for(int i = 0; i < array.length - 1; i++){

//当前值当作最小值

int min = array[i];

for(int j = i+1; j < array.length; j++){

if(min>array[j]){

//如果后面有比min值还小的就交换

min = array[j];

array[j] = array[i];

array[i] = min;

}

}

}

}

}