leetcode 874. Walking Robot Simulation

一道很基础的题。被卡在的点就是如何判断是否被阻拦住，这里采用一步一步的走，然后用set来存储所有的障碍点，这样每走一步就判断一下。

class Solution {
    public int robotSim(int[] commands, int[][] obstacles) {
        int[][] derections = new int[][]{{0,1},{-1,0},{0,-1},{1,0}};
        int derect = 0;
        int resx=0,resy=0;
        int max = 0;
        HashSet<String> set = new HashSet<>();
        for(int[] num : obstacles){
            set.add(String.valueOf(num[0])+"-"+String.valueOf(num[1]));
        }
        for(int i=0;i<commands.length;i++){
            if(commands[i]==-2){
                derect = (derect+1)%4;
            }else if(commands[i]==-1){
                derect = (derect+3)%4;
            }else{
                while(commands[i]>0&&!set.contains(String.valueOf(resx+derections[derect][0])+"-"+String.valueOf(resy+derections[derect][1]))){
                    resx += derections[derect][0];
                    resy += derections[derect][1];
                    commands[i]-=1;
                    max = Math.max(max,resx*resx+resy*resy);
                }
            }
            
        }
        return max;
    }
}

看了一下十个月前用python写的代码，简洁简单。

class Solution:
    def robotSim(self, commands: List[int], obstacles: List[List[int]]) -> int:
        obstacle = set([tuple(pos) for pos in obstacles])
        loc = [0,0]
        d = [0,1]
        max_distance = 0
        
        for i in commands:
            if i == -1:
                d[0],d[1]=d[1],-d[0]
            elif i == -2:
                d[0],d[1]=-d[1],d[0]
            elif 1<=i<=9:
                step = i
                while step>0:
                    if (loc[0]+d[0],loc[1]+d[1]) in obstacle:
                        break
                    loc[0] += d[0]
                    loc[1] += d[1]
                    step -= 1
                    max_distance = max(max_distance,loc[0]**2+loc[1]**2)
                    
        return max_distance