【笔试题】拼多多笔试

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1. 编程题1：气温采样

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分析：找出区间上重复的点。由于low_i>=-50，由于list索引从0开始。我们先加50，最后再减50即可。

可以用ArrayList，本题用数组也可以。

public static void main(String[] args) {        Scanner sc = new Scanner(System.in);        int [] list = new int [101];        int n = sc.nextInt();        int k = sc.nextInt();        for(int i = 0; i < n; i++) {            int start = sc.nextInt();            int end = sc.nextInt();            for(int j = start; j <= end; j++) {                list[j + 50] ++;            }        }        sc.close();        int minIndex = -1;        int maxIndex = -1;        for(int i = 0; i < list.length; i++) {            if(list[i] >= k) {                minIndex = i - 50;                break;            }        }        for(int i = list.length - 1; i >= 0; i--) {            if(list[i] >= k) {                maxIndex = i - 50;                break;            }        }        if(minIndex == -1)            System.out.println("error");        else             System.out.println(minIndex + " " + maxIndex);    }

2. 编程题2：小熊吃包

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分析：中间过程排序以后还要按原顺序排序。
方法1：可以先记录id，再按id排序。
方法2：还可以定义一个排序数组。

方法1：

import java.util.*;public class PingDuoDuo {    public static void main(String[] args) {        Scanner sc=new Scanner(System.in);        int n=sc.nextInt();        int m=sc.nextInt();        List<Cake> list = new ArrayList<Cake>();        for(int i=1;i<=n;i++){            int deli = sc.nextInt();            int deSpeed = sc.nextInt();            list.add(new Cake(i,deli ,deSpeed));                    }        int canEat = list.size();        //测试//      Collections.sort(list, new SortDeliANDSpeed());//      for(Cake i:list){//          System.out.println(i.deli+" "+i.deSpeed);//      }        while(canEat>0){            Collections.sort(list, new SortDeliANDSpeed());            if(list.get(0).deli>0){//可以吃，吃第一个                Cake c = list.get(0);                c.deli=-1;                canEat--;                           }            if(list.get(1).deli>0){//可以吃，吃第二个                Cake c = list.get(1);                c.deli=-1;                canEat--;                           }            //其他的新鲜度下降            for(int i=0;i<list.size();i++){                if (list.get(i).deli>0) {                    int t=list.get(i).deli-list.get(i).deSpeed;                    if(t<=0){//不能吃了                        list.get(i).deli=0;                        canEat--;                    }else{                        list.get(i).deli=t;                    }                                       }            }            if(canEat<m){                break;            }                   }        //按id排序        Collections.sort(list,new SortId());        for(int i=0;i<list.size();i++){            System.out.println(list.get(i).deli);        }           }}class Cake{    int id;    int deli;    int deSpeed;        public Cake(int id,int deli,int deSpeed) {        this.id=id;        this.deli=deli;        this.deSpeed=deSpeed;    }}class SortId implements Comparator<Cake>{    @Override    public int compare(Cake o1, Cake o2) {        return o1.id - o2.id;    }}class SortDeliANDSpeed implements Comparator<Cake>{    @Override    public int compare(Cake o1, Cake o2) {        // TODO Auto-generated method stub        if(o1.deli < o2.deli){            return 1;        }else if(o1.deli > o2.deli){            return -1;        }else{            return o2.deSpeed - o1.deSpeed;        }    }   }

方法2：

import java.util.ArrayList;import java.util.Collections;import java.util.Scanner;public class Main15 {    public static void main(String[] args){        Scanner in = new Scanner(System.in);        int n = in.nextInt();        int m = in.nextInt();        Bun[] buns = new Bun[n]; //记录了元对象的顺序        ArrayList<Bun> list = new ArrayList();        for(int i=0;i<n;i++){            int deli = in.nextInt();            int speed = in.nextInt();            buns[i] = new Bun(deli,speed);//只是做记录顺序用，因为是引用对象            list.add(buns[i]);        }        Collections.sort(list);        int s = n;        while(s>=m){            int l =2;            while (!list.isEmpty()&&l>0&&list.get(0).deli>0){               list.get(0).eat();               list.remove(0);               l--;               s--;            }           for(Bun bun: list){               if(bun.deli>0){                   bun.expired();                   if(bun.deli<=0){                       s--;                   }               }           }           Collections.sort(list);        }        for(Bun bun:buns){            System.out.println(bun.deli);        }    }    static class Bun implements Comparable{        int deli;        int speed;        public Bun(int deli,int speed){            this.deli = deli;            this.speed = speed;        }        @Override        public int compareTo(Object o) {            Bun bun =(Bun)o;            if(this.deli>bun.deli){                return -1;            }else if(this.deli==bun.deli){                if(this.speed>bun.speed){                    return -1;                }else if(this.speed==bun.speed){                    return 0;                }else{                    return 1;                }            }else{                return 1;            }        }        @Override        public String toString() {            return "Bun{" +                    "deli=" + deli +                    ", speed=" + speed +                    '}';        }        public void eat(){            this.deli = -1;        }        public void expired(){            int k = this.deli - this.speed;            if(k<0){                this.deli = 0;            }else{                this.deli = k;            }        }    }}

3. 编程题3：整数序列

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import java.util.*;public class Test {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();int [] numbers = new int [n];for(int i = 0 ; i < n; i++)numbers[i] = sc.nextInt();sc.close();int count = 1;int max = 1 << n;Set<SubList> set = new HashSet<SubList>();while(count < max) {String bits = Integer.toBinaryString(count);String key = new StringBuffer(bits).reverse().toString();  List<Integer> list = new ArrayList<Integer>();for(int i = 0; i < key.length(); i++) {if(key.charAt(i) == '1')list.add(numbers[i]);}SubList temp = new SubList(list);if(temp.valid()) {set.add(temp);/*for(int i = 0; i < temp.nums.size(); i++) {System.out.print(temp.nums.get(i) + " ");}System.out.println();*/}count++;}System.out.println(set.size());}}class SubList {public List<Integer> nums;public SubList(List<Integer> list) {this.nums = new ArrayList<Integer>(list);}public boolean valid() {if(nums.size() <= 1)return false;for(int i = 1; i < nums.size(); i++) {int i1 = nums.get(i - 1);int i2 = nums.get(i);if(i1 >= i2)return false;}return true;}@Overridepublic int hashCode() {final int prime = 31;int result = 1;result = prime * result + ((nums == null) ? 0 : nums.hashCode());return result;}@Overridepublic boolean equals(Object obj) {SubList other = (SubList) obj;for(int i = 0; i < this.nums.size(); i++) {if(this.nums.get(i) != other.nums.get(i))return false;}return true;}}

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