蓝桥杯训练 十六进制转八进制 (小模拟)

#include <cstdio>
#include <string>
#include <cmath>
#include <iostream>
#include <algorithm>
using namespace std;
int out[1000005];

int main()
{
    int n;
    scanf("%d", &n);
    while(n--)
    {
        string s, ans;
        cin >> s;
        if(s[0] == '0')
        {
            printf("0\n");
            continue;
        }
        int len = s.length();
        for(int i = len - 1; i >= 0; i--)
        {
            if(s[i] == '0')
                ans += "0000";
            else if(s[i] == '1')
                ans += "1000";
            else if(s[i] == '2')
                ans += "0100";
            else if(s[i] == '3')
                ans += "1100";
            else if(s[i] == '4')
                ans += "0010";
            else if(s[i] == '5')
                ans += "1010";
            else if(s[i] == '6')
                ans += "0110";
            else if(s[i] == '7')
                ans += "1110";
            else if(s[i] == '8')
                ans += "0001";
            else if(s[i] == '9')
                ans += "1001";
            else if(s[i] == 'A')
                ans += "0101";
            else if(s[i] == 'B')
                ans += "1101";
            else if(s[i] == 'C')
                ans += "0011";
            else if(s[i] == 'D')
                ans += "1011";
            else if(s[i] == 'E')
                ans += "0111";
            else if(s[i] == 'F')
                ans += "1111";
        }
        len = ans.length();
        if(len % 3 == 1)
        {
            len += 2;
            ans += "00";
        }
        else if(len % 3 == 2)
        {
            len += 1;
            ans += "0";
        }
        int cnt = 0;
        for(int i = 0; i < len; i += 3)
            out[cnt ++] = (ans[i] - '0') + (ans[i + 1] - '0') * 2 + (ans[i + 2] - '0') * 4;
        bool flag = false;
        for(int i = cnt - 1; i >= 0; i--)
        {
            if(out[i] == 0 && !flag)
                continue;
            flag = true;
            printf("%d", out[i]);
        }
        printf("\n");
    }   
}