Hdu 3429 Resistors (分数模板 递归读入)

2009年洛矶山区域赛 中的一题

这套题可以在 http://org.coloradomesa.edu/acm/rmrc/2009/index.html 下载标程和数据

读入部分参考了：http://hi.baidu.com/czz19891012/item/c824ca83cca60be8e496e014

第一次写分数模板，还没有用其他题目测试过，可能有bug

题意：就是算电路的总电阻，&表示串联，| 表示并联

分数存储的时候要用64位整型

#include <cstdio>#include <cstring>#include <cctype>#include <iostream>#include <string>using namespace std;#define i64 __int64class fraction{private:inline i64 Gcd (i64 x,i64 y){return y==0?x:Gcd(y,x%y);}i64 Lcm (i64 x,i64 y){x=x/Gcd(x,y)*y;if(x<0) x=-x;return x;}public:    i64 a,b;    fraction () {}    fraction (i64 x)    {        a=x; b=1;    }    fraction (i64 x,i64 y)    {        a=x; b=y;        Refresh();    }    void Refresh ()    {        if (b<0) b=-b,a=-a;        i64 k=Gcd(a,b);        if (k<0) k=-k;        a/=k; b/=k;    }fraction Inverse () const{//取倒数return fraction (b,a);}    fraction operator + (fraction p)    {        fraction ans;        ans.b=Lcm(b,p.b);        ans.a=ans.b/b*a+ans.b/p.b*p.a;        ans.Refresh();        return ans;    }    fraction operator - (fraction p)    {        fraction ans;        ans.b=Lcm(b,p.b);        ans.a=ans.b/b*a-ans.b/p.b*p.a;        ans.Refresh();        return ans;    }    fraction operator * (fraction p)    {        fraction ans;        ans.a=a*p.a;        ans.b=b*p.b;        ans.Refresh();        return ans;    }    fraction operator / (fraction p)    {        fraction ans;        ans.a=a*p.b;        ans.b=b*p.a;        ans.Refresh();        return ans;    }    bool operator < (const fraction &p) const    {        return a*p.b<b*p.a;    }    bool operator > (const fraction &p) const    {        return a*p.b>b*p.a;    }    bool operator == (const fraction &p) const    {        return a*p.b==b*p.a;    }fraction operator | (fraction p){//取倒相加取倒fraction t1=fraction (b,a);fraction t2=p.Inverse ();t1=t1+t2;return t1.Inverse();}    void print ()    {        printf("%I64d/%I64d\n",a,b);    }};string s;int len;fraction read (int &now){    int fz=0,fm=0;    int i;    for (i=now;i<len;i++)    {        if (s[i]=='/') break;        fz*=10;        fz+=s[i]-'0';    }    for (i=i+1;i<len;i++)    {        if (isdigit(s[i]))        {            fm*=10;            fm+=s[i]-'0';        }        else break;    }fraction tmp(fz,fm);    now=i-1;    return tmp;}fraction cal (int &now){    fraction ans;    int front=-1;    for (int i=now+1;i<len;i++)    {        if (s[i]=='(')        {            if(front==-1)               ans=cal(i);            else if(front==0)                ans=ans+cal(i);            else if(front==1)                ans=ans|cal(i);        }        else if (isdigit(s[i]))        {            if (front==-1)                ans=read(i);            else if (front==0)                ans=ans+read(i);            else if (front==1)                ans=ans|read(i);        }        else if (s[i]==')')        {            now=i;            return ans;        }        else if (s[i]=='&')            front=0;        else if (s[i]=='|')            front=1;    }}int main (){while (getline(cin,s)){len=s.length();fraction ans;int flag=-1; //-1:之前没有运算符, 0:之前 &, 1:之前 |for (int i=0;i<len;i++){if (s[i]=='('){if (flag==-1)ans=cal(i);else if (flag==0)ans=ans+cal(i);else if(flag==1)ans=ans|cal(i);}else if (isdigit(s[i])){if (flag==-1)ans=read(i);else if (flag==0)ans=ans+read(i);else if (flag==1) ans=ans|read(i);}else if (s[i]=='&')flag=0;else if (s[i]=='|')flag=1;}ans.print();}return 0;}