我的代码不打印其中一个测试用例的正确数字 - ＆＃34; MCMXCVI＆＃34;
应该打印：1996年。 它目前正在打印2106。
我怀疑它未能验证C＆＃39; C＆＃39;检查一个＆＃39; M＆＃39;我最后一个elif声明中的元素。但是，我输入正确，并且不知道为什么会这样。任何帮助将不胜感激！
编辑：所以我仍然无法弄明白。我知道它已经失败了＆＃34; IV＆＃34;和＆＃34; MCM＆＃34; - 但为什么？我正在解析所有内容而且它应该是 - 我绝对错过了一些东西。我需要一些n00b解释！
第二编辑：知道了！我跟踪了＃34; IV＆＃34;手工制作，超级慢慢地 - 我想出了我添加了V（5），我减去了1后，而不是添加5 - 1（4）。所以我最终得到了5.这个逻辑也失败了。我必须先检查元素的值，然后再添加。谢谢大家！
class Solution:
def romanToInt(self, roman):
"""
:type s: str
:rtype: int
"""
sum = 0
for element in range(0, len(roman)):
if roman[element] == 'I':
sum += 1
elif roman[element] == 'V':
sum += 5
if roman[element - 1] == 'I':
sum -= 1
elif roman[element] == 'X':
sum += 10
if roman[element - 1] == 'I':
sum -= 1
elif roman[element] == 'C':
sum += 100
if roman[element - 1] =='X':
sum -= 10
elif roman[element] == 'L':
sum += 50
if roman[element - 1] == 'X':
sum -= 10
elif roman[element] == 'D':
sum += 500
if roman[element - 1] == 'C':
sum -= 100
elif roman[element] == 'M':
sum += 1000
if roman[element - 1] == 'C':
sum -= 100
return sum
答案 0 :(得分：1)
由于没有普遍接受应该如何使用Roman numbers。例如。例如，来自维基百科的using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Threading;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Threading;
namespace DarnContextMenu
{
// States used for filtering what is displayed via ICollectionView
public enum EConState { Disabled, LoggedIn, LoggedOff };
// Stripped down model
public class Connection
{
public Connection (string name)
{
Name = name;
}
public EConState State { get; set; } = EConState.Disabled;
public string Name { get; set; } = string.Empty;
}
// Viewmodel
public class ConnectionVM : DependencyObject, INotifyPropertyChanged
{
// Simulation of changing States
static List<EConState> allStates = new List<EConState> { EConState.Disabled, EConState.LoggedIn, EConState.LoggedOff };
Timer t;
void changeMe (object state)
{
if (state is ConnectionVM c)
MainWindow.UIDispatcher
.Invoke (() => c.State =
allStates
.Where (s => s != c.State)
.OrderBy (_ => Guid.NewGuid ().GetHashCode ())
.First ());
}
// End of simulation of changing States
public static readonly DependencyProperty StateProperty = DependencyProperty.Register ("State", typeof (EConState), typeof (ConnectionVM),
new PropertyMetadata (EConState.Disabled, (DependencyObject d, DependencyPropertyChangedEventArgs e) =>
{
if (d is ConnectionVM vm)
{
vm.ConName = $"{vm.Connection.Name} [{(EConState)e.NewValue}]";
vm.PropertyChanged?.Invoke (vm, new PropertyChangedEventArgs (nameof (vm.State)));
}
}));
// The state of the connection: influences if the connection is shown at all and used in sorting
public EConState State
{
get { return (EConState)GetValue (StateProperty); }
set { SetValue (StateProperty, value); }
}
// name created by models basename and state - changes via callback from StateProperty
protected static readonly DependencyPropertyKey ConNamePropertyKey = DependencyProperty.RegisterReadOnly ("ConName", typeof (string), typeof (ConnectionVM), new PropertyMetadata (""));
public static readonly DependencyProperty ConNameProperty = ConNamePropertyKey.DependencyProperty;
public string ConName
{
get { return (string)GetValue (ConNameProperty); }
protected set { SetValue (ConNamePropertyKey, value); }
}
Connection Connection { get; }
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
///
/// </summary>
/// <param name="connection">The connection - used for name and initial state</param>
/// <param name="delay">a delay for the timer until the state-changes start</param>
/// <param name="period">a delay between state changes </param>
public ConnectionVM (Connection connection, TimeSpan delay, TimeSpan period)
{
t = new Timer (changeMe, this, (int)delay.TotalMilliseconds, (int)period.TotalMilliseconds);
Connection = connection;
State = Connection.State; // changing, simulated by timer inside VM
}
}
public class MainViewModel
{
// all connections - in RL: occasionally new ones will be added by the user
public ObservableCollection<ConnectionVM> Cons { get; set; }
// filtered and sorted view on Cons - Collection
public ICollectionView ConsView { get; set; }
public MainViewModel (CollectionContainer cc)
{
// demodata - normally connections are created by userinteractions
// this simulates 9 connections that change status every 4s to 10s
Cons = new ObservableCollection<ConnectionVM> (
Enumerable.Range (1, 9)
.Select (n => new ConnectionVM (new Connection ($"Connection #{n}")
, TimeSpan.FromMilliseconds (300 * n)
, TimeSpan.FromMilliseconds (700 * (n + 5))))
);
// create a sorted and filtered view
// - sort by Status and then by Name
// - show only Connecitons that are not Disabled
ConsView = new CollectionViewSource { Source = Cons }.View;
using (var def = ConsView.DeferRefresh ())
{
ConsView.SortDescriptions.Add (new SortDescription ("State", ListSortDirection.Ascending));
ConsView.SortDescriptions.Add (new SortDescription ("ConName", ListSortDirection.Ascending));
ConsView.Filter = obj => (obj is ConnectionVM vm) && vm.State != EConState.Disabled;
}
// attach a Refresh-Action of MVM to each ConnectionVMs PropertyChanged which is fired by
// ConnectionVM.StateProperty.Callback notifies each listener on StateProperty-Change
foreach (var vm in Cons)
{
vm.PropertyChanged += (s, e) => // object s, PropertyChangedEventArgs e
{
cc.Collection = ConsView;
RefreshViewModels ();
};
}
// in case the whole collection is added or removed to/from
Cons.CollectionChanged += (s, e) =>
{
cc.Collection = ConsView;
RefreshViewModels ();
};
}
void RefreshViewModels ()
{
ConsView.Refresh ();
MainWindow.logger.Content = $"Valid: {Cons.Count (c => c.State != EConState.Disabled)}/{Cons.Count ()} (In/Off/Disabled: {Cons.Count (c => c.State == EConState.LoggedIn)} / {Cons.Count (c => c.State == EConState.LoggedOff)} / {Cons.Count (c => c.State == EConState.Disabled)})";
}
}
// create a MenuItem from the ConnectionVM - in real theres a bit more code inside due to Icons, Commands, etc.
public class VmToMenuItemConverter : IValueConverter
{
public object Convert (object value, Type targetType, object parameter, CultureInfo culture)
=> new MenuItem { Header = (value as ConnectionVM).ConName ?? $"Invalid '{value.GetType ()}'" };
public object ConvertBack (object value, Type targetType, object parameter, CultureInfo culture) => null;
}
public partial class MainWindow : Window
{
public static Dispatcher UIDispatcher = null;
public static Label logger = null;
public MainWindow ()
{
UIDispatcher = Application.Current.Dispatcher;
InitializeComponent ();
logger = msgBlock;
DataContext = new MainViewModel (cc);
}
}
}
和MCMX代表MDCCCCX，您应该检查每个数字的每个次要数字，而不仅仅是前一个数字。
我可以发表的评论是：
1910中同时包含I和V减法。而对于其他更大的数字也包括所有以前较小的数字。这适用于X添加L，X和V等。I将被评估为 + 1，+ 5，-1 = + 5 而不是+4。您需要 + 1，+ 5， -2 = + 5 IV然后element=0有不同的含义（最后一个数字），你不想检查它。也许你的代码需要更多的bug修复，但这就是我找到的。