数据结构实验之栈与队列二：一般算术表达式转换成后缀式（SDUT 2132）

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int ok(char ch, char sh)
{
    if(sh == '(')return 1;
    if((ch == '*' || ch == '/' || ch == '%') && (sh == '+' || sh =='-'))
        return 1;
    else return -1;
}
int main()
{
    int i = 0,n, top = -1;
    char exp[1055], str[1005], ch;
    while(~scanf("%c", &ch) && ch != '#')
    {
        if(ch >= 'a' && ch <= 'z')exp[i++] = ch;
        else if(ch == '(') str[++top] = ch;
        else if(ch == ')')
        {
            while(top != -1)
            {
                exp[i ++] = str[top];
                top --;
                if(str[top] == '(')
                {
                    top --;
                    break;
                }
            }
        }
        else {
            if(top == -1 || ok(ch,str[top]) > 0)
            {
                str[++top] = ch;
            }
            else
            {
                while(top >= 0 && ok(ch,str[top]) < 0)
                {
                    exp[i ++] = str[top--];
                }
                str[++top] = ch;
            }
        }
    }
    while(top != -1)
    {
        exp[i++] = str[top--];
    }
    exp[i] = '\0';
    printf("%s\n",exp);
    return 0;
}