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| public static string ParseToRPN(string pattern)
{
StringBuilder Rexpression = new StringBuilder();
pattern = ReplaceUnleagalChar(pattern);
Stack<double> num = new Stack<double>();
Stack<char> oper = new Stack<char>();
StringBuilder stringBuilder = new StringBuilder();
bool flag = false;
for (int i = 0; i < pattern.Length; i++)
{
if (char.IsDigit(pattern[i]) || pattern[i] == '.' || (i == 0 && pattern[i] == '-') || (i > 0 && pattern[i - 1] == '('))
{
stringBuilder.Append(pattern[i]);
}
else
{
if (!string.IsNullOrWhiteSpace(stringBuilder.ToString()))
num.Push(double.Parse(stringBuilder.ToString()));
if (stringBuilder.Length > 1)
{
Rexpression.Append($"({stringBuilder})");
}
else
Rexpression.Append(stringBuilder.ToString());
stringBuilder.Clear();
flag = pattern[i] == '(';
PushOperators(ref oper, ref Rexpression, pattern[i]);
}
}
if (!string.IsNullOrWhiteSpace(stringBuilder.ToString()))
{
if (stringBuilder.Length > 1)
Rexpression.Append($"({stringBuilder})");
else
Rexpression.Append(stringBuilder.ToString());
}
while (oper.Count > 0)
Rexpression.Append(oper.Pop());
Console.WriteLine($"逆波兰表达式：{Rexpression}");
return Rexpression.ToString();
}
public static string ReplaceUnleagalChar(string p)
{
return p.Replace("（", "(").Replace("）", ")").Replace("÷", "/").Replace("×", "*")
.Replace("x", "*").Replace("除以", "/").Replace("除", "/").Replace("乘以", "*").Replace("乘", "*").Replace(" ", "");
}
public static void PushOperators(ref Stack<char> opers, ref StringBuilder Rexpression, char oper)
{
if (opers.Count == 0)
opers.Push(oper);
else if (oper == ')')
{
while (opers.Count != 0 && opers.Peek() != '(')
Rexpression.Append(opers.Pop());
opers.Pop();
}
else if (operators[oper] > operators[opers.Peek()])
opers.Push(oper);
else
{
while (opers.Count != 0 && opers.Peek() != '(' && operators[oper] <= operators[opers.Peek()])
Rexpression.Append(opers.Pop());
opers.Push(oper);
}
}
|
