skiing

 package noj_skiing;

 import java.util.*;

 import java.math.*;

 public class Main {

     public static void main(String[] args) {

         Solution s = new Solution();

         Scanner sc = new Scanner(System.in);

         int N = sc.nextInt();

         int[] result = new int[N];

         for(int i = 0; i < N; i++) {

             int rowNum = sc.nextInt();

             int colNum = sc.nextInt();

             int[][] info = new int[rowNum][colNum];

             for(int r = 0; r < rowNum; r++) {

                 for(int c = 0; c < colNum; c++) {

                     info[r][c] = sc.nextInt();

                 }

             }

             result[i] = s.getResult(info, rowNum, colNum);

         }

         sc.close();

         for(int i : result) {

             System.out.println(i);

         }

     }

 }

 class Solution {

     public int getResult(int[][] info, int rowNum, int colNum) {

         int max = 0;

         int[][] states = new int[rowNum][colNum]; //make sure equal 0 all

         for(int r = 0; r < rowNum; r++) {

             for(int c = 0; c < colNum; c++) {

                 max = Math.max(max, getMaxLength(info, r, c, rowNum, colNum, states));

             }

         }

         return max;

     }

     public int getMaxLength(int[][] info, int row, int col, int rowNum, int colNum, int[][] states) {

         if(row < 0 || row >= rowNum || col < 0 || col >= colNum) //如果输入的坐标越界的处理

             return 0;

         if(states[row][col] != 0) //所求位置的最大长度求过

             return states[row][col];

         int nextStep = findNextStep(info, row, col, rowNum, colNum);

         if(nextStep == 0) //所求位置在队尾

             return states[row][col] = 1;

         int maxLengthUp     = (nextStep & 8) == 8 ? getMaxLength(info, row - 1, col, rowNum, colNum, states) : 0;

         int maxLengthDown     = (nextStep & 4) == 4 ? getMaxLength(info, row + 1, col, rowNum, colNum, states) : 0;

         int maxLengthLeft     = (nextStep & 2) == 2 ? getMaxLength(info, row, col - 1, rowNum, colNum, states) : 0;

         int maxLengthRight     = (nextStep & 1) == 1 ? getMaxLength(info, row, col + 1, rowNum, colNum, states) : 0;

         return max_4(maxLengthUp, maxLengthDown, maxLengthLeft, maxLengthRight) + 1;

     }

     public int findNextStep(int[][] info, int row, int col, int rowNum, int colNum) {

         int result = 0;

         if(row != 0 && info[row - 1][col] < info[row][col])             //up

             result |= 8;

         if(row != rowNum - 1 && info[row + 1][col] < info[row][col])     //down

             result |= 4;

         if(col != 0 && info[row][col - 1] < info[row][col])             //left

             result |= 2;

         if(col != colNum - 1 && info[row][col + 1] < info[row][col])     //right

             result |= 1;

         return result;

     }

     public int max_4(int i_1, int i_2, int i_3, int i_4) {

         return Math.max(Math.max(i_1, i_2), Math.max(i_3, i_4));

     }

 }

感觉不是很难，思路一上来就可以想出来，具体一些细节的处理也没有很坑的地方。