数据结构实验之栈与队列三：后缀式求值（SDUT 2133）

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int a[10005];
char s[20005];
int main()
{
    int i,j,k,top;
    while(~scanf("%s",s))
    {
        top = 0;
        int len = strlen(s);
        for(i = 0; i < len - 1; i ++)
        {
            if(s[i] >= '0' && s[i] <= '9')
            {
                a[top ++] = s[i] - '0';
            }
            else
            {
                if(s[i] == '+')
                {
                    k = a[top - 2] + a[top - 1];
                    top --;
                    a[top - 1] = k;
                }
               else if(s[i] == '-')
                {
                    k = a[top - 2] - a[top - 1];
                    top --;
                    a[top - 1] = k;
                }
                else if(s[i] == '*')
                {
                    k = a[top - 2] * a[top - 1];
                    top --;
                    a[top - 1] = k;
                }
                else if(s[i] == '/')
                {
                    k = a[top - 2] / a[top - 1];
                    top --;
                    a[top - 1] = k;
                }
            }
        }
        printf("%d\n",a[top - 1]);
    }
    return 0;
}