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我一直在努力通过代码战，我遇到了 mazerunner ( https://www.codewars.com/kata/maze-runner/train/javascript ) 我已经被难住了大约 2 天！

function mazeRunner(maze, directions) {

//find start value  

var x = 0; //x position of the start point
var y = 0; //y position of the start point

for (var j = 0 ; j < maze.length ; j++){
if (maze[j].indexOf(2) != -1){
  x = j;
  y = maze[j].indexOf(2)
}
      } // end of starting position forloop

console.log(x + ', ' + y)


  for (var turn = 0 ; turn < directions.length ; turn++){


if (directions[turn] == "N"){
 x -= 1;
}
if (directions[turn] == "S"){
 x += 1;
}
if (directions[turn] == "E"){
 y += 1;
}
if (directions[turn] == "W"){
 y -= 1;
}

 if (maze[x][y] === 1){
 return 'Dead';
 }else if (maze[x][y] === 3){
 return 'Finish';
 }

if (maze[x] === undefined || maze[y] === undefined){
return 'Dead';
}

}

return 'Lost';

}

当我运行它时，它适用于大多数场景，但是在最后一个场景中，我收到以下错误

TypeError: Cannot read property '3' of undefined
at mazeRunner
at /home/codewarrior/index.js:87:19
at /home/codewarrior/index.js:155:5
at Object.handleError

任何帮助，将不胜感激！我把我的头发拉到这个上面！

4

1 回答 1

2

您的解决方案的问题是，移动后，您只需检查maze[x][y]

在失败的测试中，maze[x]将在某个时间点undefined（向南移动一段时间）。我想在同一点上y会是3，因此错误Cannot read property '3' of undefined

为避免这种情况，您应该在尝试访问坐标之前将测试未定义的代码向上移动：

// move this as first check
if (maze[x] === undefined || maze[y] === undefined){
  return 'Dead';
}
于 2018-06-07T20:16:02.177 回答