PAT 甲1027 火星颜色 Colors in Mars

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

Output Specification:
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 its left.

Sample Input:

15 43 71

Sample Output:

#123456

题意:
给定三个0-168的十进制整数 转为13进制
思路:
注意转为13进制还是只有1位数时，输出前面的0
C++:

#include<bits/stdc++.h>
using namespace std;
int main(){
    int num;
    char c[13] = {'0','1','2','3','4','5','6','7','8','9','A','B','C'};
    cout<<"#";
    for(int i = 0;i<3;i++){
        int ans[30],cnt=0;
        cin>>num;
        do{
            ans[cnt++] = num%13;
            num/=13;
        }while(num!=0);
        if(cnt==1) cout<<"0";
        for(int j=cnt-1;j>=0;j--) cout<<c[ans[j]];
    }    
    return 0;
}