hiho1249 Xiongnu's Land

题目链接：http://hihocoder.com/problemset/problem/1249

题目大意：有一个大正方形里面有好多不重叠的小矩形，怎么找出一条竖线分割这个正方形，使得两边的矩形面积尽量相等并且正方形左边的面积比右边大

思路：做两次二分就好了

 #include <stdio.h>
 #include <iostream>
 #include <algorithm>
 using namespace std;
 #define xx first
 #define yy second
 struct node{
     int len,wid;
     long long sum;
     pair<int,int> p1;
     pair<int,int> p2;
     void cal(){
         p2.xx=p1.xx+len;
         p2.yy=p1.yy-wid;
         sum=(long long)len*wid;
     }
 };
 bool cmp(const node&a,const node&b){
     return a.p1.xx<b.p1.xx;
 }
 const int maxn=1e4+;
 node a[maxn];
 int n,r;
 long long check(int x){
     long long tmp=;
     for(int i=;i<=n;i++){
         tmp+=((long long )a[i].wid*max(min(a[i].len,x-a[i].p1.xx),));
     }
     return tmp;
 }
 int binary_search(int R,long long sum){
     int l=-,r=R+;
     int mid;
     while(r-l>){
         mid=(l+r)>>;
         long long tmp=check(mid);
         if(tmp>=sum-tmp){
             r=mid;
         }
         else l=mid;
     }
     long long ans=check(r);
     l=-,r=R+;
     while(r-l>){
          mid=(l+r)>>;
         long long tmp=check(mid);
         if(tmp>ans) r=mid;
         else l=mid;
     }
     return l;
 }
 int main(){
     int T;
     //freopen("C:\\Users\\acm\\Desktop\\2015Beijing\\in.txt","r",stdin);
     scanf("%d",&T);
     while(T--){
         scanf("%d",&r);
         scanf("%d",&n);
         long long sum=;
         for(int i=;i<=n;i++){
             int x,y,len,wid;
             scanf("%d %d %d %d",&x,&y,&len,&wid);
             sum+=((long long)len*wid);
             a[i].len=len,a[i].wid=wid,a[i].p1=make_pair(x,y),a[i].cal();
         }
         sort(a+,a++n,cmp);
         printf("%d\n",binary_search(r,sum));
     }
     return ;
 }