[数据结构与算法]【Leetcode】ACM模式的输入处理

前言

以牛客笔试题为例，ACM模式下的输入处理示例

ZJ1 附加题 (多行多个int）

ZJ1 附加题题目地址

第一行一个int数字，第二行有多个int数字,

那我们第一个存一个数字，第二行用ArrayList存起来。

import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;

public class Main {
    public static List<Integer> list = new ArrayList<>();
    
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        while (in.hasNextInt()) { 
            list.add(in.nextInt());
        }
        System.out.println(n);
        System.out.println(list);
    }
}

ZJ2 编程题1 (int和int矩阵）

ZJ2 附加题题目地址

和第一个题目类似，矩阵这次我们用一个List<List<\Integer>>存起来：

import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;

public class Main {
    public static List<List<Integer>> matrix = new ArrayList<>();
    
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int t = in.nextInt();
        while (in.hasNextInt()) {
            List<Integer> row = new ArrayList<>();
            row.add(in.nextInt());
            row.add(in.nextInt());
            row.add(in.nextInt());
            row.add(in.nextInt());
            matrix.add(new ArrayList(row));
        }
        System.out.println(t);
        System.out.println(matrix);
    }
}

ZJ3 编程题2 (两个int和一个String）

ZJ3 附加题题目地址

一个完整的String用next()函数扫描出来

import java.util.Scanner;

public class Main {
    public static String s;
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();
        while (in.hasNext()) {
            s = in.next();
        }
        System.out.println(a + " " + b);
        System.out.println(s);
    }
}

ZJ4 附加题 (一行int）

ZJ4 附加题题目地址

可以直接放一个list中：

import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;

public class Main {
    public static List<Integer> list = new ArrayList<>();
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextInt()) {
            list.add(in.nextInt());
        }
        System.out.println(list);
    }
}

ZJ5 编程题1 (多个int多个String(字符矩阵)）

ZJ5 附加题题目地址

值得注意的是输入的字符矩阵是用多行String来给的，next()拿到String之后还要用charAt()来取其中的char。

这里要构建字符矩阵，我为了方便打印使用了List<List<>>来存，当然也可以用char[][]来存：

import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;

public class Main {
    public static List<List<Character>> chars;
    
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int row = in.nextInt();
        int col = in.nextInt();
        chars = new ArrayList<>();
        while (in.hasNext()) {
            for (int i = 0; i < row; i++) {
                List<Character> temp = new ArrayList<>();
                String rowString = in.next();
                
                for (int j = 0; j < col; j++) {
                    temp.add(rowString.charAt(j));
                }
                chars.add(temp);
            }
        }
        System.out.println(chars);
    }
}

char[][] 形式：

import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;

public class Main {
    public static char[][] chars;
    
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int row = in.nextInt();
        int col = in.nextInt();
        chars = new char[row][col];
        while (in.hasNext()) {
            for (int i = 0; i < row; i++) {
                char[] rowString = in.next().toCharArray();
                chars[i] = rowString;
            }
        }
        printFunc(chars);
    }
    
    public static void printFunc(char[][] chars) {
        for (int i = 0; i < chars.length; i++) {
            for (int j = 0; j < chars[0].length; j++) {
                System.out.print(chars[i][j]);
            }
            System.out.println();
        }
    }
}

MGJ8 链表合并

MGJ8 附加题题目地址

有两种处理方法，一种是真的老老实实按照链表处理，一种是按照数组处理（题目能A就行，怎么简单怎么来）

按照链表处理：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        ListNode list1 = createList(in.nextLine().split(" "));
        ListNode list2 = createList(in.nextLine().split(" "));
        while (list1 != null) {
            System.out.print(list1.val + " ");
            list1 = list1.next;
        }
        System.out.println();
        while (list2 != null) {
            System.out.print(list2.val + " ");
            list2 = list2.next;
        }
    }
    
    public static ListNode createList(String[] str){ 
        if (str == null || str.length == 0)
            return null;
        ListNode pre = new ListNode(0);
        ListNode head = pre;
        for (int i = 0; i < str.length; i++) {
            head.next = new ListNode(Integer.parseInt(str[i]));
            head = head.next;
        }
        return pre.next;
    }
}
1
class ListNode {
    int val;
    ListNode next;
    
    public ListNode(int val) {
        this.val = val;
    }
}

int[] 形式：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String[] s1 = in.nextLine().split(" ");
        String[] s2 = in.nextLine().split(" ");
        int[] list1 = new int[s1.length];
        int[] list2 = new int[s2.length];
        for (int i = 0; i < s1.length; i++) {
            list1[i] = Integer.parseInt(s1[i]);
            System.out.print(list1[i] + " ");
        }
        System.out.println();
        for (int j = 0; j < s2.length; j++) {
            list2[j] = Integer.parseInt(s2[j]);
            System.out.print(list2[j] + " ");
        }
    }
    
}