BUPT复试专题—科学计算器(2009)

题目描述

给你一个不带括号的表达式，这个表达式只包含加、减、乘、除，请求出这个表达式的最后结果，最后结果一定是整数；

输入

一个数学表达式，只包括数字，数字保证是非负整数，以及五种运算符 "+","-","*","/"，"="；数字和运算符之间有一个或者多个空格，运算符的总数不会超过 100，最后以"="号结尾，表示表达式结束。注意：使用 C 的同学，在读取字符串的时候请使用 scanf("%s",..);以免不必要的错误。

输出

整数；

样例输入

1 + 2 + 3 * 6 / 9 =

样例输出

来源

2009机考模拟

#include <bits/stdc++.h>

using namespace std;

char donser[100],temp[100];

int change(int num,int from)

{

    int i=from+1,x=0;

    x=temp[from]-'0';

    while(i-from<num)

    {

        x*=10;

        x+=temp[i]-'0';

        i++;

    }

    return x;

}

int main()

{

    memset(donser,0,sizeof(donser));

    memset(temp,0,sizeof(temp));

    while(gets(donser))

    {

        int i=0,j=0;

        while(donser[i]!='\0')

        {

            if(donser[i]!=' ')

                temp[j++]=donser[i];

            i++;

        }

        i=0;

        stack<int> num_stack;

        stack<char> fu_stack;

        while(temp[i]!='\0')

        {

            if(temp[i]>='0'&&temp[i]<='9')

            {

                int num=1,from=i;

                while(temp[i+1]>='0'&&temp[i+1]<='9')

                {

                    num++;

                    i++;

                }

                num_stack.push(change(num,from));

                i++;

            }

            if(!fu_stack.empty())

            {

                if(fu_stack.top()=='*'||fu_stack.top()=='/')

                {

                    int x=num_stack.top();

                    num_stack.pop();

                    int y=num_stack.top();

                    num_stack.pop();

                    if(fu_stack.top()=='*')

                        y=x*y;

                    else y=y/x;

                    num_stack.push(y);

                    fu_stack.pop();

                }

            }

            if(temp[i]=='+'||temp[i]=='-'||temp[i]=='*'||temp[i]=='/')

            {

                fu_stack.push(temp[i]);

                i++;

            }

            if(temp[i]=='=')

            {

                i++;

                continue;

            }

        }

        stack<int> num_stack_temp;

        stack<char> fu_stack_temp;

        while(!fu_stack.empty())

        {

            fu_stack_temp.push(fu_stack.top());

            fu_stack.pop();

        }

        while(!num_stack.empty())

        {

            num_stack_temp.push(num_stack.top());

            num_stack.pop();

        }

        while(!fu_stack_temp.empty())

        {

            int x=num_stack_temp.top();

            num_stack_temp.pop();

            int y=num_stack_temp.top();

            num_stack_temp.pop();

            if(fu_stack_temp.top()=='+')

                y=y+x;

            else

                y=x-y;

            num_stack_temp.push(y);

            fu_stack_temp.pop();

        }

        cout<<num_stack_temp.top()<<endl;

        num_stack_temp.pop();

        memset(donser,0,sizeof(donser));

        memset(temp,0,sizeof(temp));

    }

    return 0;

}

巴特西

BUPT复试专题—科学计算器(2009)

题目描述

输入

输出

样例输入

样例输出

来源

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