/// <summary>
/// 为表达式插入空格
/// </summary>
/// <param name="source"></param>
/// <returns></returns>
public static string InsertBlank(string source)
{
StringBuilder sb = new StringBuilder();
var list = source.ToCharArray();
foreach (var temp in list)
{
if (OperatorLevel.ContainsKey(temp.ToString()))
{
sb.Append(" ");
sb.Append(temp.ToString());
sb.Append(" ");
}
else
{
sb.Append(temp);
}
}
return(sb.ToString());
}
/// <summary>
/// 根据逆波兰表达式获取结构
/// </summary>
/// <param name="source"></param>
/// <returns></returns>
public static double GetResult(string source)
{
Stack <string> stack = new Stack <string>();
var list = source.Split(' ');
for (int i = 0; i < list.Length; i++)
{
string current = list[i];
if (Regex.IsMatch(current, "^([0-9]{1,}){1}")) // "^(-?[0-9]*[.]*[0-9]{0,3})$"))
{
stack.Push(current);
}
else if (OperatorLevel.ContainsKey(current))
{
double right = double.Parse(stack.Pop());
double left = double.Parse(stack.Pop());
stack.Push(GetValue(left, right, current[0]).ToString());
}
}
return(double.Parse(stack.Pop()));
}
/// <summary>
/// 转化为逆波兰表达式
/// </summary>
/// <param name="source"></param>
/// <returns></returns>
public static string ConvertToRPN(string source)
{
StringBuilder result = new StringBuilder();
Stack <string> stack = new Stack <string>();
string[] list = source.Split(' ');
for (int i = 0; i < list.Length; i++)
{
string current = list[i];
if (Regex.IsMatch(current, "^([0-9]{1,}){1}"))
{
result.Append(current + " ");
}
else if (OperatorLevel.ContainsKey(current))
{
if (stack.Count > 0)
{
var prev = stack.Peek();
if (prev == "(")
{
stack.Push(current);
continue;
}
if (current == "(")
{
stack.Push(current);
continue;
}
if (current == ")")
{
while (stack.Count > 0 && stack.Peek() != "(")
{
result.Append(stack.Pop() + " ");
}
//Pop the "("
stack.Pop();
continue;
}
if (OperatorLevel[current] < OperatorLevel[prev])
{
while (stack.Count > 0)
{
var top = stack.Pop();
if (top != "(" &&
top != ")")
{
result.Append(top + " ");
}
else
{
break;
}
}
stack.Push(current);
}
else
{
stack.Push(current);
}
}
else
{
stack.Push(current);
}
}
}
if (stack.Count > 0)
{
while (stack.Count > 0)
{
var top = stack.Pop();
if (top != "(" && top != ")")
{
result.Append(top + " ");
}
}
}
return(result.ToString());
}
