一些集合面试题

来源：互联网发布：淘宝东京时光隧道编辑：程序博客网时间：2024/05/19 17:08
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));}}
0 0