UVALive - 7261 Xiongnu's Land

思路：

　　先二分下界，再二分上届。

 #include <bits/stdc++.h>

 using namespace std;

 #define MP make_pair
 #define PB push_back
 typedef long long LL;
 typedef pair<int,int> PII;
 const double eps=1e-;
 const double pi=acos(-1.0);
 const int K=1e6+;
 const int mod=1e9+;

 struct node
 {
     int x,y,w,h;
     node(){}
     node(int a,int b,int c,int d){x=a,y=b,w=c,h=d;}
 }rc[K];

 LL sum,ls;
 LL check(int x,int n)
 {
     LL ret=;
     for(int i=;i<=n;i++)
     if(rc[i].x+rc[i].w<=x)
         ret+=rc[i].w*1LL*rc[i].h;
     else if(rc[i].x<=x)
         ret+=1LL*(x-rc[i].x)*rc[i].h;
     return ret;
 }
 int main(void)
 {
     //freopen("in.acm","r",stdin);
     int t;cin>>t;
     while(t--)
     {
         int R,l,r,n,ll,rr;
         sum=,ls=1e15;
         scanf("%d%d",&R,&n);
         for(int i=;i<=n;i++)
             scanf("%d%d%d%d",&rc[i].x,&rc[i].y,&rc[i].w,&rc[i].h),sum+=1LL*rc[i].w*rc[i].h;
         l=,r=R;
         while(l<=r)
         {
             int mid=l+r>>;
             LL ret=check(mid,n);
             if(ret>=sum-ret)
                 ll=mid,r=mid-;
             else
                 l=mid+;
         }
         ls=2LL*check(ll,n)-sum;
         l=ll,r=R;
         while(l<=r)
         {
             int mid=l+r>>;
             LL ret=check(mid,n);
             if(2LL*ret-sum<=ls)
                 rr=mid,l=mid+;
             else
                 r=mid-;
         }
         printf("%d\n",rr);
     }
     return ;
 }