D. Salary Changing
effect: there are n variables, each variable has a value interval, n variables required for this assignment, variables such that n does not exceed the median as large as possible and the S (n always an odd number)
bipartite answer, the median is greater than or equal mid Q can have (n + 1) / 2 are greater than or equal mid variables, greedy ordering get away.
#include<cstdio>
#include<algorithm>
using namespace std;
typedef long long i64;
const int maxn = 200002;
struct interval{
int l, r;
bool operator < (const interval &B)const{
return l < B.l;
}
}E[maxn];
bool ok(int target, int n, i64 S){
i64 cost = 0;
int cnt = 0;
for(int i=n;i>=1;--i){
if(cnt*2<n&&E[i].r>=target){
if(E[i].l>=target)cost += E[i].l;
else cost += target;
cnt++;
}else{
cost += E[i].l;
}
}
return cost<=S && cnt*2>n;
}
void work(){
i64 S;
int n;
scanf("%d%lld", &n, &S);
for(int i=1;i<=n;++i){
scanf("%d%d", &E[i].l, &E[i].r);
}
sort(E+1, E+n+1);
int L = E[n/2+1].l;
int R = 1000000000;
while(L<=R){
int mid = (L+R)>>1;
if(ok(mid, n, S))L = mid + 1;
else R = mid - 1;
}
printf("%d\n", L-1);
}
int main(){
int t;scanf("%d", &t);
while(t--){
work();
}
return 0;
}