PAT 甲级 1027 Colors in Mars

https://pintia.cn/problem-sets/994805342720868352/problems/994805470349344768

People in Mars represent the colors in their computers in a similar way as the Earth people. That is, a color is represented by a 6-digit number, where the first 2 digits are for Red, the middle 2 digits for Green, and the last 2 digits for Blue. The only difference is that they use radix 13 (0-9 and A-C) instead of 16. Now given a color in three decimal numbers (each between 0 and 168), you are supposed to output their Mars RGB values.

Input

Each input file contains one test case which occupies a line containing the three decimal color values.

Output

For each test case you should output the Mars RGB value in the following format: first output "#", then followed by a 6-digit number where all the English characters must be upper-cased. If a single color is only 1-digit long, you must print a "0" to the left.

Sample Input

15 43 71

Sample Output

#123456

代码：

#include <bits/stdc++.h>
using namespace std;

const int maxn = 1e5 + 10;
char s[maxn];
char a[15] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C'};

void num(int n) {
    int cnt = 0;
    if(n == 0) printf("00");
    else {
        while(n != 0) {
        s[cnt ++] = a[n % 13];
        n /= 13;
        }

        if(cnt == 1)
            printf("0%s", s);
        else {
            for(int i = cnt - 1; i >= 0; i --)
                printf("%c", s[i]);
        }
    }

}

int main() {
    int x, y, z;
    scanf("%d%d%d", &x, &y, &z);
    printf("#");
    num(x);
    num(y);
    num(z);
    printf("\n");
    return 0;
}