POJ2295 A DP Problem 解一元方程（只有加减没有乘除没有括号）

POJ2295 A DP Problem 解一元方程（只有加减没有乘除没有括号）

#include < iostream >
#include < string >
#include < cmath >
using   namespace  std;

int  Case;
char   in [ 400 ];


int  main()
{
    cin>>Case;
    int pos;
    int i,j,k,m,n,len,cur,sumint_left,sumint_right,sumx_left,sumx_right;
    float sumx,sumint;
    float res;
    bool left;
    bool lastchar;
    while(Case--)
    {
        cin>>in;
        len=strlen(in);
        sumint_left=0;
        sumint_right=0;
        sumx_left=0;
        sumx_right=0;
        cur=0;
        left=1;
        for(i=0;i<len;i++)
            if(in[i]=='=')
                break;
        pos=i;
        lastchar=1;
        for(i=0;i<pos;i++)
        {
            if(in[i]=='x')
            {
                if(lastchar)
                    sumx_left++;
                else
                    sumx_left--;
                i++;
                if(i==pos)
                    break;
                else if(in[i]=='+')
                    lastchar=1;
                else lastchar=0;
            }
            else
            {
                cur=0;
                for(j=i;j<pos&&in[j]>='0' && in[j]<='9';j++)
                {
                    cur*=10;
                    cur+=in[j]-'0';
                }
                if(j==pos)
                {
                    if(lastchar)
                        sumint_left+=cur;
                    else 
                        sumint_left-=cur;
                    break;
                }
                else
                {
                    if(in[j]=='x')
                    {
                        if(lastchar)
                            sumx_left+=cur;
                        else 
                            sumx_left-=cur;
                        j++;
                        if(j==pos)
                            break;
                        else if(in[j]=='+')
                                lastchar=1;
                        else lastchar=0;
                        i=j;
                    }
                    else
                    {
                        if(lastchar)
                            sumint_left+=cur;
                        else sumint_left-=cur;
                        if(in[j]=='+')
                            lastchar=1;
                        else lastchar=0;
                        i=j;
                    }
                }
            }
        }
        lastchar=1;
        for(i=pos+1;i<len;i++)
        {
            if(in[i]=='x')
            {
                if(lastchar)
                    sumx_right++;
                else sumx_right--;
                i++;
                if(i==len)
                    break;
                else if(in[i]=='+')
                    lastchar=1;
                else
                    lastchar=0;
            }
            else
            {
                cur=0;
                for(j=i;j<len && in[j]<='9' && in[j]>='0';j++)
                {
                    cur*=10;
                    cur+=in[j]-'0';
                }
                if(j==len)
                {
                    if(lastchar)
                        sumint_right+=cur;
                    else
                        sumint_right-=cur;
                    break;
                }
                else
                {
                    if(in[j]=='x')
                    {
                        if(lastchar)
                            sumx_right+=cur;
                        else 
                            sumx_right-=cur;
                        j++;
                        if(j==pos)
                            break;
                        else    if(in[j]=='+')
                            lastchar=1;
                        else
                            lastchar=0;
                        i=j;
                    }
                    else
                    {
                        if(lastchar)
                            sumint_right+=cur;
                        else
                            sumint_right-=cur;
                        if(in[j]=='+')
                            lastchar=1;
                        else 
                            lastchar=0;
                        i=j;
                    }
                }
            }
        }
    //    cout<<sumx_left<<"        "<<sumx_right<<"         "<<sumint_left<<"        "<<sumint_right<<endl;
        if(sumx_left==sumx_right)
        {
            if(sumint_left==sumint_right)
                cout<<"IDENTITY"<<endl;
            else
                cout<<"IMPOSSIBLE"<<endl;
        }
        else
        {
            sumx=sumx_left-sumx_right;
            sumint=sumint_right-sumint_left;
            res=sumint/sumx;
            cout<<floor(res)<<endl;
        }
    }
    return 0;
}