【BZOJ】3850: ZCC Loves Codefires（300T就这样献给了水题TAT）

#include <cstdio>
#include <cstring>
#include <cmath>
#include <string>
#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#include <sstream>
using namespace std;
typedef long long ll;
#define pb push_back
#define rep(i, n) for(int i=0; i<(n); ++i)
#define for1(i,a,n) for(int i=(a);i<=(n);++i)
#define for2(i,a,n) for(int i=(a);i<(n);++i)
#define for3(i,a,n) for(int i=(a);i>=(n);--i)
#define for4(i,a,n) for(int i=(a);i>(n);--i)
#define CC(i,a) memset(i,a,sizeof(i))
#define read(a) a=getint()
#define print(a) printf("%d", a)
#define dbg(x) cout << (#x) << " = " << (x) << endl
#define error(x) (!(x)?puts("error"):0)
#define rdm(x, i) for(int i=ihead[x]; i; i=e[i].next)
inline int getint() { static int r, k; r=0,k=1; static char c; c=getchar(); for(; c<‘0‘||c>‘9‘; c=getchar()) if(c==‘-‘) k=-1; for(; c>=‘0‘&&c<=‘9‘; c=getchar()) r=r*10+c-‘0‘; return k*r; }

const int N=1e5+10;
struct dat { int x, y; }a[N];
ll ans;
int n;
bool cmp(const dat &a, const dat &b) { return a.y*a.x+b.y*(a.x+b.x)<b.y*b.x+a.y*(a.x+b.x); }
int main() {
	read(n);
	rep(i, n) read(a[i].x);
	rep(i, n) read(a[i].y);
	sort(a, a+n, cmp); ll sum=0;
	rep(i, n) sum+=a[i].x, ans+=sum*a[i].y;
	cout << ans;
	return 0;
}