Hackealo Test JS

relieve = [[9, 2, 2, 2, 3, 5], 
           [9, 8, 3, 2, 4, 5], 
           [9, 7, 2, 2, 4, 3], 
           [9, 9, 2, 4, 4, 3], 
           [9, 2, 3, 4, 3, 5]];

function is_border(posx, posy, relieve){
    var current = relieve[posy][posx];
    var maxx = relieve[0].length;
    var maxy = relieve.length;
    if(posy >= 1 && relieve[posy - 1][posx] < current){
      return 0;
    }
    if(posy <= (maxy - 2) && relieve[posy + 1][posx] < current){
      return 0;
    }
    if(posx >= 1 && relieve[posy][posx - 1] < current){
      return 0;
    }
    if(posx <= (maxx - 2) && relieve[posy][posx + 1] < current){
      return 0;
    }
    return 1;    
}

function encontrar_bordes(relieve){
  var ret = new Array();
  for (y = 0; y < relieve.length; y++) { 
    ret[y] = new Array();
    for (x = 0; x < relieve[y].length; x++) {
        ret[y][x] = is_border(x, y, relieve);
  	}
  }
  return ret;  
}

var ret = encontrar_bordes(relieve);
console.log(ret);