codevs 1213 解的个数（我去年打了个表 - -）

Posted 2020-07-13 一入OI深似海

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int T,x,y,ans,g,l1,r1,l2,r2;
int init()
{
    int x=0;char s=getchar();bool f=0;
    while(s<‘0‘||s>‘9‘){if(s==‘-‘)f=1;s=getchar();}
    while(s>=‘0‘&&s<=‘9‘){x=x*10+s-‘0‘;s=getchar();}
    if(f)return -x;return x;
}
void E_gcd(int a,int b)
{
    if(b==0)
      {
          x=1;y=0;g=a;
      }
    else 
      {
          E_gcd(b,a%b);
          int tmp=x;
          x=y;
          y=tmp-a/b*y;
      }
}
int main()
{
    int a,b,c,i,j;
    T=init();
    while(T--)
      {
          ans=0;
          a=init();b=init();c=init();
          c=-c;
          l1=init();r1=init();l2=init();r2=init();
          if(a==0&&b==0)
            {
                if(c!=0||l1>r1||l2>r1)
                  {
                      printf("0\n");
                    continue;
              }
            long long an,li,ri;
            li=r1-l1+1;ri=r2-l2+1;
            an=li*ri;
                cout<<an<<endl;
                continue;
          }
          if(a==0)
            {
                y=c/b;
                if(y<l2||y>r2||c%b!=0)
                  printf("0\n");
                else 
                  printf("1\n");
                continue;
          }
        if(b==0)
            {
                x=c/a;
                if(x<l1||x>r1||c%a!=0)
                  printf("0\n");
                else 
                  printf("1\n");
                continue;
          }
          E_gcd(a,b);
          if(c%g!=0)
            {
                printf("0\n");
                continue;
          }
        int s=c/g;
        x*=s;y*=s;
          int ai=a/g;
        int bi=b/g;
        if(x<l1)
          {
              while(x<l1)
              {
                x+=bi;y-=ai;
              }
              for(i=x;i<=r1;i+=bi,y-=ai)
                if(y>=l2&&y<=r2)
                  ans++;
          }
        else if(x>r1)
          {
              while(x>r1)
              {
                x-=bi;y+=ai;
              }
              for(i=x;i>=l1;i-=bi,y+=ai)
                if(y>=l2&&y<=r2)
                  ans++;
          }
        else 
          {
              int yi=y;
              for(i=x;i<=r1;i+=bi,yi-=ai)
                if(yi>=l2&&yi<=r2)
                  ans++;
            yi=y+ai;
            for(i=x-bi;i>=l1;i-=bi,yi+=ai)
                if(yi>=l2&&yi<=r2)
                  ans++;
          }
          printf("%d\n",ans);
      }
    return 0;
}