题解 | 大整数哈希

import sys
def solve():
    try:
        line=sys.stdin.readline()
        if not line:
            return
        n=int(line.strip())
    except ValueError:
        return
    
    f={}
    mod=2**64
    total=0
    for i in range(1,n+1):
        line=sys.stdin.readline().strip()
        if not line:
            return
        parts=list(map(int,line.split()))
        x=parts[0]
        y=parts[1]

        ans=f.get(x,0)
        f[x]=y
        total=(total+i*ans)&(mod-1)
    
    print(total)

if __name__=="__main__":
    solve()