一些集合面试题

package com.fly;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class Test {

	public static void main(String[] args) {	
		int[] a={3,5,6,7,2,3,32,12,34,5,256};
		
		int[] b={1,2,3,4,5,6,7};
		
		System.out.println(Arrays.toString(union(a,b)));
		
		
		System.out.println(Arrays.toString(allin(a,b)));
		
		System.out.println(Arrays.toString(minus(a,b)));
		
		double[] da={1,2,3,4,5};
		double[] db={1,1,1,1,1,1};
		moving(da, db, 3);
		
		moving2(da, db, 3);
		
	}
	
	public static Object[] union(int[] a1,int[] a2){
		Set<Integer> set=new HashSet<Integer>();
		for(int i=0;i<a1.length;i++){
			set.add(a1[i]);
		}
		for(int j=0;j<a2.length;j++){
			set.add(a2[j]);
		}
		return set.toArray();
	}
	
	public static Object[] allin(int[] a1,int[] a2){
		Map<Integer,Boolean> map=new HashMap<Integer,Boolean>();
		for(int i=0;i<a1.length;i++){
			if(!map.containsKey(a1[i])){
				map.put(a1[i], Boolean.FALSE);
			}
		}
		for(int i=0;i<a2.length;i++){
			if(map.containsKey(a2[i])){
				map.put(a2[i], Boolean.TRUE);
			}
		}
		List<Integer> list=new ArrayList<Integer>();
		for(Iterator<Integer> i=map.keySet().iterator();i.hasNext();){
			Integer a=i.next();
			if(map.get(a)){
				list.add(a);
			}
		}
		return list.toArray();
	}

	public static Object[] minus(int[] a1,int[] a2){
		List<Integer> list=new LinkedList<Integer>();
		List<Integer> history=new LinkedList<Integer>();
		for(int i=0;i<a1.length;i++){
			if(!list.contains(a1[i])){
				list.add(a1[i]);
			}
		}
		for(int i=0;i<a2.length;i++){
			if(list.contains(a2[i])){
				history.add(a2[i]);
				list.remove(a2[i]);
			}else{
				if(!history.contains(a2[i])){
					list.add(a2[i]);
				}
			}
		}
		
		return list.toArray();
	}
	
	
	public static void moving(double[] a,double[] b,int k){
		int n=a.length>b.length?b.length:a.length;
		for(int i=0;i<n;i++){
			int count=0;
			double total=0;
			for(int j=i;count<k&&j>=0;j--,count++){
				total=total+a[j];
			}
			System.out.println("total--->"+total);
			System.out.println("count--->"+count);
			b[i]=total/count;
		}
		System.out.println(Arrays.toString(b));
	}
	public static void moving2(double[] a,double[] b,int k){
		int n=a.length>b.length?b.length:a.length;
		for(int i=0;i<n;i++){
			int count=0;
			double total=0;
			if(i<k){
				for(int j=i;count<k&&j>=0;j--,count++){
					total=total+a[j];
				}
				System.out.println("total--->"+total);
				System.out.println("count--->"+count);
				b[i]=total/count;
			}else{
				b[i]=(b[i-1]*k+a[i]-a[i-k])/k;
			}
			
		}
		System.out.println(Arrays.toString(b));
	}
}