C++ :

#include <iostream>
using namespace std;

void decimalToHex(int n) {
    char hex[100];
    int i = 0;
    
    if (n == 0) {
        cout << "0" << endl;
        return;
    }
    
    while (n > 0) {
        int remainder = n % 16;
        if (remainder < 10)
            hex[i++] = remainder + '0';  // 0-9
        else
            hex[i++] = remainder - 10 + 'A';  // A-F
        n /= 16;
    }

    // 输出十六进制时需要逆序
    for (int j = i - 1; j >= 0; j--) {
        cout << hex[j];
    }
    cout << endl;
}

int main() {
    int n;
    cin >> n;
    decimalToHex(n);
    return 0;
}