题解 | 大整数哈希

#include <iostream>
#include <map>
#include <cstdint>
using namespace std;
int main(){
    int n;
    unsigned long long x,y;               //使用unsigned long long类型存储x与y
    uint64_t sum=0;                       //使用uint64_t类型存储sum，保证sum始终是对2^64取模后的结果
    cin>>n;
    map<unsigned long long,unsigned long long> m;
    for(long long i=1;i<=n;i++){
        cin>>x>>y;
        if(m.find(x)!=m.end())
            sum+=i*m[x];
        m[x]=y;
    }
    cout<<sum;
    return 0;
}