题意：n(n为奇数)个员工，每个员工的薪水在li-ri之间，一共有s元，使得员工薪水中位数最大。
二分...
#include<bits/stdc++.h>
using namespace std;
#define ll long long
int l[200005],r[200005];
ll s1;
int main()
{int t;cin>>t;while(t--){int n;ll s;cin>>n>>s;int h=(n+1)/2;s1=0;int ans;for(int i=0;i<n;i++)cin>>l[i]>>r[i],s1+=l[i];int l1=1,r1=1e9;while(l1<=r1){int mid=(l1+r1)>>1;vector<int>v;for(int i=0;i<n;i++){if(r[i]>=mid)v.push_back(max(0,mid-l[i]));}sort(v.begin(),v.end());if(v.size()<h)r1=mid-1;else{ll s2=accumulate(v.begin(),v.begin()+h,0ll);//cout<<mid<<" "<<s1<<" "<<s2<<endl;if(s1+s2<=s)ans=mid,l1=mid+1;else r1=mid-1;}}cout<<ans<<endl;}
}