数据结构算法——1022. 波兰表达式

用栈存数据，遇见符号抽两个数据计算即可

#include
using namespace std;

string* stack[120];
double data[120];
int size = 0;

int main()
{
    string s;
    while(cin >> s)
    {
        string* ss = new string;
        ss->erase();
        ss->append(s);
        stack[size++] = ss;
        if(cin.get() == 'n')
            break;
    }

    //  for(int i = 0; i < size; i++)
    //      cout << *stack[i] << endl;
    
    int Dsize = 0;
    while(size )
    {
        size--;
        if(*stack[size] == "+")
        {
            double a = data[--Dsize];
            double b = data[--Dsize];
            double c = a + b;
            data[Dsize++] = c;
        }
        else if(*stack[size] == "-")
        {
            double a = data[--Dsize];
            double b = data[--Dsize];
            double c = a - b;
            data[Dsize++] = c;
        }
        else if(*stack[size] == "*")
        {
            double a = data[--Dsize];
            double b = data[--Dsize];
            double c = a * b;
            data[Dsize++] = c;
        }
        else if(*stack[size] == "/")
        {
            double a = data[--Dsize];
            double b = data[--Dsize];
            double c = a / b;
            data[Dsize++] = c;
        }
        else
        {
            char str[10];
            for(int i = 0; i < 10; i++)
                str[i] = 0;
            for(int i = 0; i < stack[size]->length(); i++)
            {
                str[i] = stack[size]->at(i);
            }
            data[Dsize++] = atof(str);
        }

        // for(int i = 0; i < Dsize; i++)
        //     cout << data[i] <<" ";
        // cout << endl;
    }
    printf("%.6fn",data[--Dsize]);

}