Python嵌套for循环遍历二维数组实现停车查询返回False如何解决

原有代码的错误点 #

• 循环逻辑错误：外层循环直接遍历行元素而非行索引y，内层循环错误遍历整个二维列表spots而非当前行的列索引x，无法获取正确的坐标值
• 取值逻辑错误：判断车位类型时直接拿整个二维列表spots和字符对比，没有取对应坐标spots[y][x]的车位标识进行判断
• 逻辑运算优先级错误：and优先级高于or，原有条件写法例如vehicle == "small" and spots == "S" or spots == "R"实际等价于(vehicle == "small" and spots == "S") or (spots == "R")，只要车位是R不管车辆类型都会命中，逻辑完全不符合要求
• 提前返回错误：在单次循环判断的else分支直接返回False，导致第一个车位不符合要求时就直接终止遍历返回结果，不会检查后续车位

修复后的代码 #

def whereCanIPark(spots, vehicle):
    # 遍历行获取行号y
    for y in range(len(spots)):
        current_row = spots[y]
        # 遍历列获取列号x
        for x in range(len(current_row)):
            current_spot = current_row[x]
            # 按停车规则判断
            if vehicle == "regular" and current_spot == "R":
                return [x, y]
            elif vehicle == "small" and (current_spot == "S" or current_spot == "R"):
                return [x, y]
            elif vehicle == "motorcycle" and (current_spot == "S" or current_spot == "R" or current_spot == "M"):
                return [x, y]
    # 所有车位遍历完无符合条件的再返回False
    return False

print(whereCanIPark(
  [
    # 列号为X
    # 0    1    2    3    4    5
    ['s', 's', 's', 'S', 'R', 'M'], # 0 行号为Y
    ['s', 'M', 's', 'S', 'r', 'M'], # 1
    ['s', 'M', 's', 'S', 'r', 'm'], # 2
    ['S', 'r', 's', 'm', 'r', 'M'], # 3
    ['S', 'r', 's', 'm', 'r', 'M'], # 4
    ['S', 'r', 'S', 'M', 'M', 'S']  # 5
  ],
  'regular'
))

运行结果 #

修复后代码输出为[4, 0]，与预期一致。

内容的提问来源于stack exchange，提问作者Jeepofun