题解 | 大整数哈希

#include <bits/stdc++.h>
#include <cstdint>
using namespace std;
const unsigned long long N=0xFFFFFFFFFFFFFFFF+1;
unsigned long long a,b;
unsigned long long ans=0;
map<unsigned long long,unsigned long long> m;
int n;
int main() {
    cin>>n;
    for(long long i=1;i<=n;i++)
    {
        cin>>a>>b;
        ans/=N;
        if(m.find(a)!=m.end())
        {
            ans+=i*m[a];
        }
        m[a]=b;
    }
    cout<<ans<<endl;
    return 0;
}