java算法题

Question

写一个算法：有10000000种不同的整型数。发现其最大的100要素。实施时应执行速度的优化。

Answer 1

[code="java"]
import java.util.ArrayList;

public class createDir {
private static int num[] =new int [10000000];
private static ArrayList ans=null;
public static void main(String[] arg){
for(int i = 0;i num[i]= i+1;
}
boolean boo=true;
int i = 0;
while (boo) {
int j = (int) (Math.random() * 10000000);
int k = num[i];
num[i] = num[j];
num[j] = k;
i++;
if(i==100000){
boo =false;
}
}
long start =System.currentTimeMillis();
ans = new ArrayList();
for(int j = 0;j if(j ans = sort(ans,num[j]);
}else{
if(num[j]>(Integer)ans.get(0)){
ans = getMaxValue(ans,num[j]);
}
}
}
long end =System.currentTimeMillis();
long total= (end-start);
System.out.println(total + " ms");
System.out.println(ans);
}
private static ArrayList getMaxValue(ArrayList ans,int num){
for(int i=1;i if(num ans.add(i,num);
ans.remove(0);
break;
}
if(i==ans.size()-1){
ans.add(num);
ans.remove(0);
break;
}
}
return ans;
}
private static ArrayList sort(ArrayList ans,int num){
if(ans.size()>0){
int min = (Integer) ans.get(0);
if(min>num){
ans.add(0, num);
}else if(ans.size()==1){
ans.add(num);
}else{
for(int i=1;i<ans.size();i++){
if(num < (Integer) ans.get(i)){
ans.add(i,num);
break;
}
if(i==ans.size()-1){
ans.add(num);
break;
}
}
}
}else{
ans.add(0, num);
}

    return ans;
}

}
[/code]