skiing

 1 package noj_skiing;
 2 
 3 import java.util.*;
 4 import java.math.*;
 5 
 6 public class Main {
 7 
 8     public static void main(String[] args) {
 9         Solution s = new Solution();
10         Scanner sc = new Scanner(System.in);
11         int N = sc.nextInt();
12         int[] result = new int[N];
13         for(int i = 0; i < N; i++) {
14             int rowNum = sc.nextInt(); 
15             int colNum = sc.nextInt();
16             int[][] info = new int[rowNum][colNum];
17             for(int r = 0; r < rowNum; r++) {
18                 for(int c = 0; c < colNum; c++) {
19                     info[r][c] = sc.nextInt();
20                 }    
21             }
22             result[i] = s.getResult(info, rowNum, colNum);
23         }
24         sc.close();
25         for(int i : result) {
26             System.out.println(i);
27         }
28     }
29 
30 }
31 class Solution {
32     public int getResult(int[][] info, int rowNum, int colNum) {
33         int max = 0;
34         int[][] states = new int[rowNum][colNum]; //make sure equal 0 all
35         for(int r = 0; r < rowNum; r++) {
36             for(int c = 0; c < colNum; c++) {
37                 max = Math.max(max, getMaxLength(info, r, c, rowNum, colNum, states));
38             }    
39         }
40         return max;
41     }
42     public int getMaxLength(int[][] info, int row, int col, int rowNum, int colNum, int[][] states) {
43     
44         if(row < 0 || row >= rowNum || col < 0 || col >= colNum) //如果输入的坐标越界的处理
45             return 0;
46         if(states[row][col] != 0) //所求位置的最大长度求过
47             return states[row][col];
48         
49         int nextStep = findNextStep(info, row, col, rowNum, colNum);
50         if(nextStep == 0) //所求位置在队尾
51             return states[row][col] = 1;
52         int maxLengthUp     = (nextStep & 8) == 8 ? getMaxLength(info, row - 1, col, rowNum, colNum, states) : 0;
53         int maxLengthDown     = (nextStep & 4) == 4 ? getMaxLength(info, row + 1, col, rowNum, colNum, states) : 0;
54         int maxLengthLeft     = (nextStep & 2) == 2 ? getMaxLength(info, row, col - 1, rowNum, colNum, states) : 0;
55         int maxLengthRight     = (nextStep & 1) == 1 ? getMaxLength(info, row, col + 1, rowNum, colNum, states) : 0;
56                 
57         return max_4(maxLengthUp, maxLengthDown, maxLengthLeft, maxLengthRight) + 1;
58     }
59     public int findNextStep(int[][] info, int row, int col, int rowNum, int colNum) {
60         int result = 0;
61         
62         if(row != 0 && info[row - 1][col] < info[row][col])             //up
63             result |= 8;
64         if(row != rowNum - 1 && info[row + 1][col] < info[row][col])     //down
65             result |= 4;
66         if(col != 0 && info[row][col - 1] < info[row][col])             //left
67             result |= 2;
68         if(col != colNum - 1 && info[row][col + 1] < info[row][col])     //right
69             result |= 1;
70         
71         return result;
72     }
73     public int max_4(int i_1, int i_2, int i_3, int i_4) {
74         return Math.max(Math.max(i_1, i_2), Math.max(i_3, i_4));
75     }
76 }

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。