1019 数字黑洞 (20)

思想：
主要使用 algorithm 库的自动排序算法
#include <stdio.h>
#include <algorithm>

using namespace std;

int array[4] = {0};

void val_to_array(int val)
{
    int i = 0;
    while (val != 0)
    {
        array[i] = val % 10;
        val = val / 10;
        i++;
    }
}

bool cmp (int a, int b)
{
    return a > b;
}

int array_to_val (int * num )
{
    int result = 0;
    int i = 0;
    int pred = 1;
    for (i = 0; i < 4; i++)
    {
        result += array[i] * pred;
        pred *= 10;
    }

    return result;
}

int main (void)
{
    int val = 0;
    int result = 0;
    int Min, Max;

    scanf ("%d", &val);

    while (1)
    {
        val_to_array(val);

        sort(array, array + 4);
        Max = array_to_val(array);

        sort(array, array + 4, cmp);
        Min = array_to_val(array);

        val = Max - Min;

        printf ("%04d - %04d = %04d
", Max, Min, val);

        if ((val) == 0 || (val) == 6174)    break;
    }

    return 0;

    return 0;
}