// Your task is to make a function that can take any non-negative integer as an argument and return it with its digits in descending order. Essentially, rearrange the digits to create the highest possible number.
// Examples:

// Input: 42145 Output: 54421

// Input: 145263 Output: 654321

// Input: 123456789 Output: 987654321

#include <inttypes.h>

const char triamgle[101] = "o........."
                           "oo........"
                           "ooo......."
                           "oooo......"
                           "ooooo....."
                           "oooooo...."
                           "ooooooo..."
                           "oooooooo.."
                           "ooooooooo."
                           "oooooooooo";

uint64_t descendingOrder(uint64_t n)
{
    uint64_t a, p, r;

    a = n;
    p = 1;
    r = 0;

    for(; a / 10; r += a % 10 * p, p *= 10, a /= 10)
        if(triamgle[a % 100] == '.')
            return descendingOrder(r + p * ((a / 100 * 100) + a % 10 * 10 + a / 10 % 10));
    return n;
}