米哈游0319笔试

第一次写//

发一下昨晚做题的思路 时间不够用啊 第三题有运行错误 没调试出来

只有第一题并查集全a了

package travers;

import java.util.Scanner;

public class mihay {
    static int n;
    static int m;
    static char[][] board, board2;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        m = sc.nextInt();
        String[] s = new String[n];
        board = new char[n][m];
        for (int i = 0; i < n; i++){
            s[i] = sc.next();
            board[i] = s[i].toCharArray();
        }
        int res = 0;
        int res1 = 0;
        board2 = new char[n][m];
        for (int i = 0; i < n; i++){
            for (int j = 0; j < m; j++){
                board2[i][j] = board[i][j] == 'G' ? 'B' : board[i][j];
            }
        }
        for (int i = 0; i < n; i++){
            for (int j = 0; j < m; j++){
                if (board[i][j] != 'q'){
                    res++;
                    dfs(board, i, j, board[i][j]);
                }
                if (board2[i][j] != 'q'){
                    res1++;
                    dfs(board2, i, j, board2[i][j]);
                }
            }
        }
        System.out.println(res - res1);
    }
    public static void dfs(char[][] board, int i, int j, char temp){
        if (i < 0 || j < 0 || i > n - 1 || j > m - 1 || board[i][j] != temp ||board[i][j] == 'q') {
            return;
        }
        char tmp = board[i][j];
        board[i][j] = 'q';
        dfs(board, i-1, j, tmp);
        dfs(board, i+1, j, tmp);
        dfs(board, i, j-1, tmp);
        dfs(board, i, j+1, tmp);
    }
}

第二题 哈希映射0.5（不知道为啥） 、

package travers;

import java.util.HashMap;
import java.util.Scanner;

public class mihay2 {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        for (int i = 0; i < n; i++){
            String s = sc.next();
            String t = sc.next();
            String s1 = s.length() > t.length() ? s : t;
            String t1 = s.length() > t.length() ? t : s;
            HashMap<Character, Integer> map = new HashMap<>();

            for (int j = 0; j < s1.length(); j++){
                char ch = s1.charAt(j);
                map.put(ch, map.getOrDefault(ch, 0) + 1);
            }
            boolean flag = true;
            for (int j = 0; j < t1.length(); j++){
                char ch2 = t1.charAt(j);
                if (!map.containsKey(ch2)){
                    flag = false;
                    break;
                }
                map.put(ch2, map.get(ch2) - 1);
            }
            if (flag){
                for (Character ch : map.keySet()){
                    if (ch == 'm' || ch == 'h' || ch == 'y' || map.get(ch) == 0) {
                        continue;
                    }
                    flag = false;
                    break;
                }
            }
            if (map.get('m') != map.get('h') || map.get('m') != map.get('y') || !flag)
                System.out.println("No");
            else
                System.out.println("Yes");
        }
    }
}

第三题感觉是个子集dfs的思路 但是呢找不到错哪

package travers;

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

public class mihay3 {
    static List<List<Integer>> res = new ArrayList<>();
    static List<Integer> tmp = new ArrayList<>();
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] a = new int[n];
        for (int i = 0; i < n; i++){
            a[i] = sc.nextInt();
        }
        dfs(a, 0);
        System.out.println(res.size());
    }
    public static void dfs(int[] nums, int startInd){
        if (tmp.size() >= 2){
            if (isValid(tmp)){
                res.add(new ArrayList<>(tmp));
            }
            else
                return;
        }
        for (int i = startInd; i < nums.length; i++){
            tmp.add(nums[i]);
            dfs(nums, i + 1);
            tmp.remove(tmp.size() - 1);
        }
    }
    public static boolean isValid(List<Integer> nums){
        if (nums.size() == 2){
            int a = nums.remove(nums.size()-1);
            int b = nums.remove(nums.size()-1);
            return a % b == 0 ? true : false;
        }
        int a = nums.remove(nums.size()-1);
        int b = nums.remove(nums.size()-1);
        int temp = a / b;
        while (!tmp.isEmpty()){
            a = b;
            b = nums.remove(nums.size()-1);
            if (a / b != temp)
                return false;
        }
        return true;
    }
}

第二题第三题有没有大神指导一下