A - Uint47 calculator（快速乘取模）

In the distant space, there is a technologically advanced planet.

One day they provided the Earth with a code that could achieve the ultimate meaning of the universe. People were very happy, but found that this code can only run on computers with a word length of 47 bits. As a good computer scientist, you need to implement a tool to simulate running this code on our computer.

This tool needs to simulate the following instructions:

“def x n” : define a unsigned 47 bits integer variable named x, with initial value n, n is an integer in [0, 2^47-1]

“add x y” : means x = x + y

“sub x y” : means x = x - y

“mul x y” : means x = x * y

“div x y” : means x = x / y, we guarantee y is not zero

“mod x y” : means x = x % y, we guarantee y is not zero

When the result of addition and multiplication cannot be represented by 47 bits, the part above 47 bits is truncated.

When the result of subtraction is less than zero, the result should add 2^47.

The name of each variable only contains letters and the length does not greater than 20.

Input
Contains multiple lines of input, one instruction per line.

Output
For each instruction, output the value of the first argument after calculation. For example, “def abc 100”, then your output will be “abc = 100” in a line with no quotation marks.

See Sample Output for more information.

Sample Input
def six 6
def abc 1
def bcd 0
sub bcd abc
add abc six
def universe 0
mul abc six
add universe abc
div bcd six
mod bcd abc
Sample Output
six = 6
abc = 1
bcd = 0
bcd = 140737488355327
abc = 7
universe = 0
abc = 42
universe = 42
bcd = 23456248059221
bcd = 5

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <map>
typedef long long ll;
using namespace std;
const ll mod=1LL<<47;
map<string,ll> mp;
ll mul_mod(ll x,ll y)//快速乘取模
{
    ll ans=0;
    while(y)
    {
        if(y&1) ans=(ans+x)%mod;
        y>>=1;
        x=(x+x)%mod;
    }
    return ans;
}
int main()
{
    ios::sync_with_stdio(false);
    string a,b,c;
    while(cin>>a>>b)
    {
        if(a=="def")
        {
            ll x;
            cin>>x;
            mp[b]=x;
            cout<<b<<" = "<<x<<endl;
            continue;
        }
        cin>>c;
        if(a[0]=='a')
        {
            mp[b]=(mp[c]+mp[b])%mod;
            cout<<b<<" = "<<mp[b]<<endl;
        }
        else if(a[0]=='s')
        {
            mp[b]=(mp[b]-mp[c]+mod)%mod;
            cout<<b<<" = "<<mp[b]<<endl;
        }
        else if(a[0]=='d')
        {
            mp[b]/=mp[c];
            mp[b]=(mp[b]+mod)%mod;
            cout<<b<<" = "<<mp[b]<<endl;
        }
        else if(a=="mod")
        {
            mp[b]%=mp[c];
            cout<<b<<" = "<<mp[b]<<endl;
        }
        else
        {
            mp[b]=mul_mod(mp[b],mp[c]);
            cout<<b<<" = "<<mp[b]<<endl;
        }
    }
    return 0;
}