表达方式:
“(a[i]+{-1}*(8-9))”
应该返回 true,因为这样编写语法是有效的。每个左括号在正确的位置都有一个右闭合器,并且所有括号都处于合法位置。
我尝试通过一个堆栈来做到这一点,我知道我错在哪里,但我想知道解决这个问题的相关方法。
谢谢!
我可怜可怜的错误代码:
string expression = "( a[i]+{-1}*(8-9) ) ";
Stack<char> expStack = new Stack<char>();
List<char> rightBracketsHolder = new List<char>();
for (int i = 0; i < expression.Length; i++)
{
if (expression[i] == '{')
{
expStack.Push('}');
Console.Write("}" + " ");
}
else if (expression[i] == '(')
{
expStack.Push(')');
Console.Write(")" + " ");
}
else if (expression[i] == '[')
{
expStack.Push(']');
Console.Write("]" + " ");
}
}
Console.WriteLine();
for (int i = 0; i < expression.Length; i++)
{
if (expression[i] == '}')
{
rightBracketsHolder.Add('}');
Console.Write(expression[i] + " ");
}
else if (expression[i] == ')')
{
rightBracketsHolder.Add(')');
Console.Write(expression[i] + " ");
}
else if (expression[i] == ']')
{
rightBracketsHolder.Add(']');
Console.Write(expression[i] + " ");
}
}
Console.WriteLine();
bool stackResult = checkValidity(expStack, rightBracketsHolder);
if (stackResult)
Console.WriteLine("Expression is Valid.");
else
Console.WriteLine("\nExpression is not valid.");
Console.ReadKey();
}
private static bool checkValidity(Stack<char> expStack, List<char> leftBracketsHolder)
{
Console.WriteLine();
int length = leftBracketsHolder.Count;
for (int i = 0; i < length; i++)
{
if (expStack.Peek().ToString().Contains(leftBracketsHolder.ToString()))
{
leftBracketsHolder.Remove(expStack.Peek());
expStack.Pop();
}
}
if (expStack.Count == 0 && leftBracketsHolder.Count ==0)
{
return true;
}
return false;
}
}
这段代码将解决你的目的 -
static void Main(string[] args)
{
bool error = false;
var str = "( a[i]+{-1}*(8-9) )";
Stack<char> stack = new Stack<char>();
foreach (var item in str.ToCharArray())
{
if (item == '(' || item == '{' || item == '[')
{
stack.Push(item);
}
else if(item == ')' || item == '}' || item == ']')
{
if (stack.Peek() != GetComplementBracket(item))
{
error = true;
break;
}
}
}
if (error)
Console.WriteLine("Incorrect brackets");
else
Console.WriteLine("Brackets are fine");
Console.ReadLine();
}
private static char GetComplementBracket(char item)
{
switch (item)
{
case ')':
return '(';
case '}':
return '{';
case ']':
return '[';
default:
return ' ';
}
}
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