第一題、模擬涂色游戲

import java.util.*;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String inHand = sc.nextLine();
        String toPrint = sc.nextLine();
        if(inHand==null || inHand.length()==0 || toPrint==null || toPrint.length()==0) System.out.println(0);
        char[] colors = inHand.toCharArray();
        char[] boards = toPrint.toCharArray();
        HashMap<Character, Integer> map = new HashMap<>();
        for (int i = 0; i < colors.length; i++) {
            if(Character.isUpperCase(colors[i])){
                map.put(colors[i],map.getOrDefault(colors[i],0)+1);
            }
        }
        int count = 0;
        for (int i = 0; i < boards.length; i++) {
            if(Character.isUpperCase(boards[i])){
                if(map.containsKey(boards[i]) && map.get(boards[i])>=1){
                    map.put(boards[i],map.get(boards[i])-1);
                    count++;
                }
            }
        }
        System.out.println(count);
    }
}

第二題 迷宮dfs

//    輸入描述
//    多組資料，第1行有1個正整數T，表示有T組資料，（T<=100）
//
//    對于每組資料，第1行有兩個整數N和M，(1<=N, M<=1000)
//
//    接著N行，每行有一個長度為M的字串，表示N*M的迷宮，
//
//    輸出描述
//    輸出一個整數，表示使用特異功能的最少次數，如果小昆蟲不能走出迷宮，則輸出-1，
import java.util.Arrays;
import java.util.Scanner;

    public class Main {
        static boolean flag;
        static int ans;
        static int[][] dir = new int[][] { { -1, 0 }, { 1, 0 }, { 0, -1 }, { 0, 1 } };
        static boolean[][] vis;
        static int[][] cost;

        public static void main(String[] args) {
            Scanner in = new Scanner(System.in);
            int T = in.nextInt();
            int n, m, sx, sy;
            char[][] map;

            while (T-- > 0) {
                n = in.nextInt();
                m = in.nextInt();
                in.nextLine();
                map = new char[n][m];
                vis = new boolean[n][m];
                cost = new int[n][m];
                for (int i = 0; i < n; i++) {
                    map[i] = in.next().toCharArray();
                    Arrays.fill(cost[i], 0x3f3f3f3f);
                }
                sx = 0;
                sy = 0;
                for (int i = 0; i < n; i++) {
                    for (int j = 0; j < m; j++) {
                        if (map[i][j] == '@') {
                            sx = i;
                            sy = j;
                        }
                    }
                }
                flag = false;
                vis[sx][sy] = true;
                dfs(sx, sy, map, n, m);
                if (flag) {
                    System.out.println(0);
                    continue;
                }
                flag = false;
                ans = Integer.MAX_VALUE;
                cost[sx][sy] = 0;
                dfs(sx, sy, map, n, m, cost[sx][sy]);
                System.out.println(flag ? ans : -1);
            }
        }

        static void dfs(int x, int y, char[][] map, int n, int m) {
            if (flag)
                return;
            for (int i = 0; i < 4; i++) {
                int dx = x + dir[i][0], dy = y + dir[i][1];
                // 出界了
                if (!check(dx, dy, n, m)) {
                    flag = true;
                } else if (!vis[dx][dy] && map[dx][dy] == '.') {
                    vis[dx][dy] = true;
                    dfs(dx, dy, map, n, m);
                }
            }
        }

        static void dfs(int x, int y, char[][] map, int n, int m, int cnt) {
            for (int i = 0; i < 4; i++) {
                int dx = x + dir[i][0], dy = y + dir[i][1];
                // 出界了
                if (!check(dx, dy, n, m)) {
                    flag = true;
                    ans = Math.min(ans, cnt);
                } else if (map[dx][dy] != '#') {
                    if (map[dx][dy] == '*' && cost[x][y] + 1 < cost[dx][dy]) {
                        cost[dx][dy] = cost[x][y] + 1;
                        dfs(dx, dy, map, n, m, cost[dx][dy]);
                    } else if (map[dx][dy] == '.' && cost[x][y] < cost[dx][dy]) {
                        cost[dx][dy] = cost[x][y];
                        dfs(dx, dy, map, n, m, cost[dx][dy]);
                    }
                }
            }
        }

        static boolean check(int x, int y, int n, int m) {
            return x >= 0 && y >= 0 && x < n && y < m;
        }
    }