题目描述

blablabla

样例

import java.util.*;

class Main {
    public static int n,k,res;
    public static int dx[] = {0,+1,0,-1};//遍历的方向(右下左上)
    public static int dy[] = {+1,0,-1,0};
    public static String brr[] = new String[25];  //读取数据
    public static int isth[] = new int[30]; //判断字母是否走过
    public static char arr[][] = new char[25][25];
    public static void main (String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        k = sc.nextInt();
        for (int i = 0; i < n; i++) brr[i] = sc.next();
        for (int i = 0; i < n; i++) arr[i] = brr[i].toCharArray();
        isth[arr[0][0] - 64] = 1;
        dfs(0,0,1);
        System.out.println(res);

    }


    public static void dfs (int x,int y,int step) {

        for (int i = 0; i < 4; i++) {
            int a = x + dx[i];
            int b = y + dy[i];
            if (a >= 0 && a < n && b >= 0 && b < k && isth[arr[a][b] - 64] != 1 ) {
                isth[arr[a][b] - 64]++;
                dfs(a,b,step+1);
                isth[arr[a][b] - 64]--;
            }
        }

        res = getMax(res,step);



    }



    public static int getMax(int x, int y) {
        return x > y ? x:y;
    }
}

算法1

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

C++ 代码

blablabla

算法2

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

C++ 代码

blablabla