3438. Number system conversion

Find the conversion of any two non negative integers with different bases （2 Base number ∼ 16 Base number ）, The integer given is in int Within the scope of .

The symbols of different bases are （0,1,…,9,a,b,…,f） perhaps （0,1,…,9,A,B,…,F）

Input format

There is only one line of input , Contains three integers a,n,b.a It means the following n yes a Hexadecimal integer ,b Express the desire to a Hexadecimal integer n convert to b Hexadecimal integer .

a,b It's a decimal integer .

Data may contain leading zeros .

Output format

The output contains a line , This line has an integer for the converted b Hexadecimal number .

When output, all alphabetic symbols are in upper case , namely （0,1,…,9,A,B,…,F）.

Data range

2≤a,b≤16,
A given a Hexadecimal integer n The value range in decimal system is [1,2147483647].

sample input ：

15 Aab3 7

sample output ：

210306

Code ：

#include <bits/stdc++.h>

using namespace std;

int ctoi(char c)
{
    
    if (c <= '9')
        return c - '0';
    if (c <= 'Z')
        return c - 'A' + 10;
    return c - 'a' + 10;
}

char itoc(int x)
{
    
    if (x < 10)
        return '0' + x;
    else
        return 'A' + x - 10;
}

int main()
{
    
    int a, b;
    string num;
    cin >> a >> num >> b;

    int n = 0;
    for (auto c: num)
        n = n * a + ctoi(c);

    string res;
    while (n)
        res += itoc(n % b), n /= b;
    reverse(res.begin(),res.end());
    
    cout << res << endl;
    
    return 0;
}