HNU 12817 Shipura（表达式求值）

  1 #include<cstdio>
  2 #include<cstring>
  3 #include<iostream>
  4 #include<algorithm>
  5 #include<deque>
  6 #include<cstdlib>
  7 using namespace std;
  8 typedef long long INT;
  9 const INT MOD = 1000000007; 
 10 const int maxn = 2000000+5;
 11 char str[maxn],temp[maxn];
 12 int get_num(INT s,INT t)
 13 {
 14     for(int i = 0;i < t;++i)
 15     {
 16         s = s >> 1;
 17         if(s == 0)
 18         return 0;
 19     }
 20     return s;
 21 }
 22 int main()
 23 {
 24     while(gets(temp))
 25     {
 26         if(temp[0] == ‘#‘)
 27         break;
 28         int len = strlen(temp),f = 0;
 29         for(int i = 0;i < len; ++i)
 30         if(temp[i] != ‘ ‘)
 31         str[f++] = temp[i];
 32         str[f] = NULL;
 33         len = f;
 34         deque<INT> que1;
 35         deque<char> que2;
 36         //预处理
 37         for(int i = 0;i < len-2;++i)
 38         if(str[i] == ‘>‘ && str[i+1] == ‘>‘ && str[i+2] != ‘>‘)
 39         str[i] = str[i+1] = ‘^‘;
 40         char ss[20];       //缓存数字
 41         for(int i = 0;i < len;++i)
 42         {
 43             if(str[i] == ‘S‘  || str[i] == ‘s‘)
 44             {
 45                 i++;
 46                 que2.push_front(‘<‘);
 47             }
 48             if(str[i] == ‘>‘)
 49             {
 50                 INT tt = *que1.begin();
 51                 que1.pop_front();
 52                 que2.pop_front();    //计算完后把‘<‘弹出来
 53                 tt *= tt;
 54                 tt %= MOD;
 55                 if(*que2.begin() == ‘^‘)
 56                 {
 57                     INT tt2 = *que1.begin();
 58                     que1.pop_front();
 59                     que1.push_front(get_num(tt2,tt));
 60                     que2.pop_front();
 61                 }
 62                 else que1.push_front(tt);
 63             }
 64             if(str[i] == ‘^‘)
 65             {
 66                 i++;
 67                 que2.push_front(‘^‘);
 68             }
 69             if(str[i] >= ‘0‘ && str[i] <= ‘9‘)
 70             {
 71                 int ll = 0;
 72                 while(str[i] >= ‘0‘ && str[i] <= ‘9‘)
 73                 {
 74                     ss[ll++] = str[i];
 75                     i++;
 76                 }
 77                 i--;
 78                 ss[ll] = NULL;
 79                 int tt = atoi(ss);
 80                 if(*que2.begin() == ‘^‘)
 81                 {
 82                     int tt2 = *que1.begin();
 83                     que1.pop_front();
 84                     que2.pop_front();
 85                     que1.push_front(get_num(tt2,tt));  //get_num计算tt2 >> tt之后压回到栈中
 86                 }
 87                 else que1.push_front(tt);
 88             }
 89         }
 90         while(!que2.empty())
 91         {
 92             if(*que2.begin() == ‘^‘)
 93             {
 94                 que2.pop_front();   //现在只可能剩下^
 95                 int tt1 = *que1.begin();
 96                 que1.pop_front();
 97                 int tt2 = *que1.begin();
 98                 que1.pop_front();
 99                 que1.push_front(get_num(tt2,tt1));
100             }
101     /*        else if(*que2.begin() == ‘>‘)
102             {
103                 INT tt = *que1.begin();
104                 que1.pop_front();
105                 tt *= tt;
106                 tt %= MOD;
107                 que1.push_front(tt);
108                 que2.pop_front();
109                 que2.pop_front();
110             }*/
111         }
112         printf("%d\n",*que1.begin());
113         que2.clear();
114         que1.clear();
115     }
116     return 0;
117 }