适当的使用偏置矩阵

 1 /**
 2 使用if语句
 3 */
 4 class Solution {
 5     int X = 0;
 6     int Y = 0;
 7     Set<String> set;
 8     public int robotSim(int[] commands, int[][] obstacles) {
 9         int ans = 0;
10         set = new HashSet<>(); 
11         for(int[] x : obstacles){
12             set.add(x[0]+"|"+x[1]);
13         }
14         int count = 0;
15         for(int i = 0; i < commands.length; i++){
16             if(commands[i] == -1) count = (count+1)%4;
17             else if(commands[i] == -2) count = (count+3)%4;
18             else{
19                 isObs(obstacles,X, Y, count,commands[i] );
20                 ans = Math.max(ans,X*X+Y*Y);
21             }
22         }
23         return ans;
24     }
25 
26     
27     public void isObs(int[][] obstacles,int x, int y, int count,int com ){
28         if(count == 0){
29             for(int i = 0; i < com; i++){
30                 Y++;
31                 if(set.contains(X+"|"+Y)){
32                     Y--;
33                     return ;
34                 }
35             }
36         }
37         else if(count == 2){
38             for(int i = 0; i < com; i++){
39                 Y--;
40                 if(set.contains(X+"|"+Y)){
41                     Y++;
42                     return ;
43                 }
44             }
45         }
46         else if(count == 1){
47             for(int i = 0; i < com; i++){
48                 X++;
49                 if(set.contains(X+"|"+Y)){
50                     X--;
51                     return ;
52                 }
53             }
54         }
55         else if(count == 3){
56             for(int i = 0; i < com; i++){
57                 X--;
58                 if(set.contains(X+"|"+Y)){
59                     X++;
60                     return ;
61                 }
62             }
63         }
64     }
65 
66 }

 1 class Solution {
 2     int X = 0;
 3     int Y = 0;
 4     Set<String> set;
 5     public int robotSim(int[] commands, int[][] obstacles) {
 6         int ans = 0;
 7         set = new HashSet<>(); 
 8         for(int[] x : obstacles){
 9             set.add(x[0]+"|"+x[1]);
10         }
11         int[] dx = {0,1,0,-1};
12         int[] dy = {1,0,-1,0};
13         int count = 0;
14         for(int i = 0; i < commands.length; i++){
15             if(commands[i] == -1) count = (count+1)%4;
16             else if(commands[i] == -2) count = (count+3)%4;
17             else{
18                for(int j = 0; j < commands[i]; j++){
19                     X += dx[count];
20                     Y += dy[count];
21                     if(set.contains(X+"|"+Y)){
22                         X -= dx[count];
23                         Y -= dy[count];
24                         break;
25                     }    
26                 }            
27                 ans = Math.max(ans,X*X+Y*Y);
28             }
29         }
30         // System.out.println(X+"|"+Y);
31         return ans;
32     }
33 }