129行24点全解问题，欢迎指教！

[linxi729778865]

using System;
using System.Collections.Generic;
using System.Text;

class TwentyFourProblem
{
    static void Main()
    {
        string datas = "";
        string operators = @"+_-_*_/_|_\";
        string temData = "";
        for (int i = 0; i < 4; i++)
            datas += Console.ReadLine() + "_";
        List<string> dataPermutations = new List<string>();
        List<string> operatorsCombinations = new List<string>();
        List<string> solutions = new List<string>();
        AllPermutation(datas, temData, dataPermutations);
        AllCombination(1, 3, operators, "", operatorsCombinations);
        foreach (string temDatas in dataPermutations)
            foreach (string temOperators in operatorsCombinations)
            {
                calculate(temDatas, temOperators, "", "", solutions);
            }
        foreach (string solution in solutions)
            Console.Write(solution + "\n");
        Console.Write("over");
    }


    private static void AllPermutation(string datas, string temData, List<string> permutations)
    {
        string[] data = datas.Split('_');
        for (int i = 0; i < data.Length - 1; i++)
        {
            if (data.Length == 2)
            {
                string temPermutation = temData + data[i];
                permutations.Add(temPermutation);
            }
            else
            {
                string tem = temData;
                temData += data[i] + '_';
                datas = "";
                for (int j = 0; j < data.Length - 1; j++)
                    if (j != i)
                        datas += data[j] + '_';
                AllPermutation(datas, temData, permutations);
                temData = tem;
            }
        }
    }

    private static void AllCombination(int rankCount, int rank, string datas, string temCombination, List<string> combinations)
    {
        string[] data = datas.Split('_');
        for (int i = 0; i < data.Length; i++)
        {
            if (rankCount == rank)
                combinations.Add(temCombination + data[i]);
            else
            {
                string temStr = temCombination;
                temCombination += data[i] + "_";
                AllCombination(++rankCount, rank, datas, temCombination, combinations);
                rankCount--;
                temCombination = temStr;
            }
        }
    }

    private static void calculate(string datas, string operators, string lastOperator, string temSolution, List<string> solutions)
    {
        string[] data = datas.Split('_');
        string[] temOperator = operators.Split('_');
        if (data.Length > 1)
        {
            string result = operatorOperation(data[0], data[1], temOperator[0]).ToString();
            if ((temOperator[0] == "\\" && lastOperator != "") || (temOperator[0] == "|" && (lastOperator == "-" || lastOperator == "+" || lastOperator == "|")) || ((temOperator[0] == "*" || temOperator[0] == "/") && (lastOperator == "+" || lastOperator == "-" || lastOperator == "|")))
            {
                temSolution = temSolution.Insert(0, "(");
                temSolution += ")";
            }
            if (data.Length == 4)
                temSolution += data[0];
            if (temOperator[0] == "|" || temOperator[0] == "\\")
            {
                string temOp = "";
                if (temOperator[0] == "|")
                    temOp = "-";
                else temOp = "/";
                temSolution = temSolution.Insert(0, data[1] + temOp);
            }
            else temSolution += temOperator[0] + data[1];
            string newDatas = "";
            string newOperators = "";
            for (int j = 2; j < data.Length; j++)
                newDatas += data[j] + "_";
            newDatas = newDatas.Insert(0, result + "_");
            for (int j = 1; j < temOperator.Length; j++)
                newOperators += temOperator[j] + "_";
            if (newOperators == "")
                newOperators = "?";
            calculate(newDatas.Substring(0, newDatas.Length - 1), newOperators.Substring(0, newOperators.Length - 1), temOperator[0], temSolution, solutions);
        }
        else if (data.Length == 1)
        {
            if (Math.Abs(double.Parse(data[0]) - 24) <= 0.000001)
                solutions.Add(temSolution);
        }
    }

    private static double operatorOperation(string data1, string data2, string Operator)
    {
        double result = 0;
        double num1 = double.Parse(data1);
        double num2 = double.Parse(data2);
        switch (Operator)
        {
            case "+": result = num1 + num2; break;
            case "-": result = num1 - num2; break;
            case "*": result = num1 * num2; break;
            case "/": result = num1 / num2; break;
            case "|": result = num2 - num1; break;
            case "\\": result = num2 / num1; break;
        }
        return result;
    }
}

[lihanbing]

顶

[Arcan]

不错。
唯一缺点就是如果录入相同数字的话就会出现完全相同的结果，看起来不那么舒服，如果能把这些相同的结果剔除就更好了。

[636f6c696e]

这算法不错，看起来很清晰简洁。

[threenewbee]

代码可以再精简下，如果用linq的话。