HDU1296 Polynomial Problem

http://acm.hdu.edu.cn/showproblem.php?pid=1296
随手练习
  1 #include <bits/stdc++.h>
  2 using namespace std;
  3 #define ll long long
  4 int n;
  5 char s[12345];
  6 ll Solve(string s,int i)
  7 {
  8     ll num=0;
  9     int l=i-1;
 10     int r=i+1;
 11     string s1="";
 12     while(s[l]>='0'&&s[l]<='9')
 13     {
 14         s1+=s[l];
 15         l--;
 16     }
 17     reverse(s1.begin(),s1.end());
 18     ll ans=0;
 19     ll sum=0;
 20     int len=s1.length();
 21     for(int j=0; j<len; j++)
 22     {
 23         ans*=10;
 24         ans+=(s1[j]-'0');
 25     }
 26     if(ans==0){
 27         ans=1;
 28 
 29     }
 30     if(s[r]=='^')
 31     {
 32         r++;
 33         while(s[r]>='0'&&s[r]<='9')
 34         {
 35             sum*=10;
 36             sum+=(s[r]-'0');
 37             r++;
 38         }
 39         ll pos=n;
 40         for(int j=1; j<sum; j++)
 41         {
 42             pos*=n;
 43         }
 44         num+=pos*ans;
 45     }
 46     else
 47     {
 48         num+=ans*n;
 49     }
 50     i=r;
 51     if(s[l]=='-')
 52     {
 53         num*=-1;
 54     }
 55     return num;
 56 }
 57 int main()
 58 {
 59     while(~scanf("%d",&n))
 60     {
 61         ll x=0;
 62         scanf("%s",s);
 63         int len=strlen(s);
 64         if((s[0]>='0'&&s[0]<='9')||s[0]=='X')
 65         {
 66             string s1="";
 67             int i=0;
 68             int pos=0;
 69             int flag=0;
 70             for(i=0; s[i]!='+'&&s[i]!='-'&&i<len; i++)
 71             {
 72                 s1+=s[i];
 73                 if(s[i]=='X')
 74                 {
 75                     flag=1;
 76                     pos=i;
 77                 }
 78             }
 79             if(flag)
 80             {
 81                 x+=Solve(s1,pos);
 82                 flag=0;
 83             }
 84             else
 85             {
 86                 ll ans=0;
 87                 for(int j=0; j<s1.length(); j++)
 88                 {
 89                     ans*=10;
 90                     ans+=(s1[j]-'0');
 91                 }
 92                 x+=ans;
 93             }
 94             for(int j=i; j<len;)
 95             {
 96                 if(s[j]=='-'||s[j]=='+')
 97                 {
 98                     string s2="";
 99                     s2+=s[j];
100                     j++;
101                     int ans=0;
102                     while(s[j]!='-'&&s[j]!='+'&&j<len)
103                     {
104                         s2+=s[j];
105                         ans++;
106                         if(s[j]=='X')
107                         {
108                             pos=ans;
109                             flag=1;
110                         }
111                         //cout<<s[j]<<endl;
112                         j++;
113                     }
114                     if(flag)
115                     {
116                         x+=Solve(s2,pos);
117                         flag=0;
118                     }
119                     else
120                     {
121                         ll ans=0;
122                         for(int j=1; j<s2.length(); j++)
123                         {
124                             ans*=10;
125                             ans+=(s2[j]-'0');
126                         }
127                         if(s2[0]=='-')
128                         {
129                             ans*=-1;
130                         }
131                         x+=ans;
132                     }
133                     flag=0;
134                 }
135             }
136             cout<<x<<endl;
137         }
138         else
139         {
140             int flag=0;
141             int pos=0;
142             string s3="";
143             s3+=s[0];
144             int i;
145             for(i=1; s[i]!='-'&&s[i]!='+'&&i<len; i++)
146             {
147                 s3+=s[i];
148                 if(s[i]=='X')
149                 {
150                     flag=1;
151                     pos=i;
152                 }
153             }
154             if(flag)
155             {
156                 x+=Solve(s3,pos);
157                 flag=0;
158             }
159             else
160             {
161                 ll ans=0;
162                 for(int j=1; j<s3.length(); j++)
163                 {
164                     ans*=10;
165                     ans+=(s3[j]-'0');
166                 }
167                 if(s3[0]=='-')
168                 {
169                     ans*=-1;
170                 }
171                 x+=ans;
172             }
173             flag=0;
174             for(int j=i; j<len;)
175             {
176                 if(s[j]=='-'||s[j]=='+')
177                 {
178                     string s2="";
179                     s2+=s[j];
180                     j++;
181                     int ans=0;
182                     while(s[j]!='-'&&s[j]!='+'&&j<len)
183                     {
184                         s2+=s[j];
185                         ans++;
186                         if(s[j]=='X')
187                         {
188                             pos=ans;
189                             flag=1;
190                         }
191                         //cout<<s[j]<<endl;
192                         j++;
193                     }
194                     if(flag)
195                     {
196                         x+=Solve(s2,pos);
197                         flag=0;
198                     }
199                     else
200                     {
201                         ll ans=0;
202                         for(int j=1; j<s2.length(); j++)
203                         {
204                             ans*=10;
205                             ans+=(s2[j]-'0');
206                         }
207                         if(s2[0]=='-')
208                         {
209                             ans*=-1;
210                         }
211                         x+=ans;
212                     }
213                     flag=0;
214                 }
215             }
216             cout<<x<<endl;
217         }
218     }
219     return 0;
220 }