7-31 掉入陷阱的数字

#include <stdio.h>

int calculate(int n) {
    int result, sum = 0;

    while (n>0) {
        sum += n % 10;
        n /= 10;
    }
    result = 3 * sum + 1;

    return result;
}

int main(void) {
    int num, i, result, temp;

    scanf("%d", &num);
    temp = num;
    for (i = 1;; i++) {
        result = calculate(temp);
        printf("%d:%d\n", i, result);
        if (temp == result) {
            break;
        }
        temp = result;
    }

    return 0;
}