Map和Set习题

Posted 2022-05-19 *平芜尽处是春山*

Map和Set习题

• 力扣138. 复制带随机指针的链表
• • 力扣771. 宝石与石头
  • • 牛客网.旧键盘 (20)

力扣138. 复制带随机指针的链表

class Solution 
    public Node copyRandomList(Node head) 
        if(head == null) 
            return null;
        

        Map<Node,Node> nodeMap = new HashMap<> ();
        for(Node x = head; x != null;x = x.next) 
            Node newNode = new Node(x.val);
            nodeMap.put(x,newNode);
        
        for(Node x = head; x != null;x = x.next) 
            nodeMap.get(x).next = nodeMap.get(x.next);
            nodeMap.get(x).random = nodeMap.get(x.random);
        
        return nodeMap.get(head);
    

运行截图：

力扣771. 宝石与石头

class Solution 
    public int numJewelsInStones(String jewels, String stones) 
        Set<Character> jewelSet = new HashSet<> ();
        for(int i = 0;i < jewels.length();i++) 
            jewelSet.add(jewels.charAt(i));
        
        int ret = 0;
        for(int i = 0;i < stones.length();i++) 
            if(jewelSet.contains(stones.charAt(i))) 
                ret++;
            
        
        return ret;
    

运行截图：

牛客网.旧键盘 (20)

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main 
    public static void main(String[] args) 
        Scanner scanner=new Scanner(System.in);
        String expectedStr=null;
        String actualStr=null;
        while(scanner.hasNext()) 
            expectedStr=scanner.next();
            actualStr=scanner.next();
        
        expectedStr =expectedStr.toUpperCase();
        actualStr =actualStr.toUpperCase();
        Set<Character> actualSet=new HashSet<>();
        for (int i = 0; i < actualStr.length(); i++) 
            actualSet.add(actualStr.charAt(i));
        
        Set<Character> ret=new HashSet<>();
        for (int i = 0; i < expectedStr.length(); i++) 
            char c=expectedStr.charAt(i);
            if (! actualSet.contains(c))
                if (ret.add(c))
                    System.out.print(c);
                
            
        
        System.out.println();
    

运行截图：