1237.txt

浙江大学研究生复试上机题目及解答。欢迎大家下载。

#include<stack>
#include<cstdio>
using namespace std;

stack<double> s1;
stack<char> s2;

inline void get(double&lf, char& ch)
{
    scanf("%lf",&lf);
    ch = getchar();
    while(ch==' ' || ch=='\t')
        ch=getchar();
}

int index(char ch)
{
    if(ch == '+' || ch == '-') return 1;
    else if(ch == '*' || ch == '/') return 2;
    else return 0;
}

inline double operate(double & a, double & b, char ch)
{
    switch(ch)
    {
    case '/':
        return a / b;
    case '-':
        return a - b;
    case '*':
        return a * b;
    case '+':
        return a + b;
    }
}

int main()
{
    double lf, temp;
    char ch, ch2;

    while(true)
    {
        while(!s1.empty()) s1.pop();
        while(!s2.empty()) s2.pop();
        get(lf, ch);
        if(lf == 0.0 && (ch == '\n' || ch == EOF)) break;
        while(true)
        {
            if(s2.empty() || index(s2.top()) < index(ch))
            {
                s1.push(lf);
                s2.push(ch);
            }
            else
            {
                while(!s2.empty() && index(s2.top()) >= index(ch))
                {
                    temp = s1.top();
                    s1.pop();
                    ch2 = s2.top();
                    s2.pop();
                    temp = operate(temp, lf, ch2);
                    lf = temp;
                }
                s1.push(lf);
                s2.push(ch);
            }
            if(ch == '\n') break;
            get(lf, ch);
        }
        printf("%.2lf\n",s1.top());
    }
  return 0;
}