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BB:

蒟蒻太菜了，就不寫解析了，放一個看的比較懂的大佬的部落格吧

程式碼：

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define re register
#define gc getchar
#define pc putchar
#define cs const

inline int getint(){
	re int num;
	re char c;
	while(!isdigit(c=gc()));num=c^48;
	while(isdigit
 
(c=gc()))num=(num<<1)+(num<<3)+(c^48);
	return num; 
}

cs int N=50004;
typedef pair<int,int> pii;
pii a[N];
inline bool cmp(cs pii &a,cs pii &b){
	return min(a.first,b.second)==min(b.first,a.second)?a.first<a.second:min(a.first,b.second)<min(b.first,a.second);
}

ll c[N]
 
,sum;
int T,n;
signed main(){
	T=getint();
	while(T--){
		n=getint();
		for(int re i=1;i<=n;++i){
			a[i].first=getint();
			a[i].second=getint();
		}
		sort(a+1,a+n+1,cmp);
		sum=0;
		for(int re i=1;i<=n;++i){
			sum+=a[i].first;
			c[i]=max(c[i-1],sum)+a[i].second;
		}
		cout<<c[n]<<
 
endl;
	}
	return 0;
}