题解 | 进制转换

#include <iostream>
#include <string>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <map>
#include <algorithm>
#include <vector>
#include <set>
#include <queue>//队列
#include <stack> //栈
//#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
#define endl '\n'
#define pii pair<int, int>
//queue<int> que;
//set<int> s;
//stack<int> st;



void solve() {
    //scanf("%d", &);
    //printf("\n", );

    /*
    cout << "手慢无" << endl;
    cout << "骗你的，手快也无" << endl;
    cout << "haha ^_^" << endl;
    */

    //vector<int>a(n);
    //sort(a.begin(), a.end());
    //map<int, int>mp;

    string s;
    cin>>s;
    int len=s.size();

    ll sum=0;
    ll t=1;
    for(int i=len-1;i>=2;i--)
    {
        if(s[i]>='A'&&s[i]<='Z') sum+=(s[i]-'A'+10)*t;
        else sum+=(s[i]-'0')*t;
        t*=16;
    }
    cout<<sum;

}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    //cin >> t;
    while (t--) {
        solve();
        cout << endl;
    }
    return 0;
}