Untitled

    int sum = 0, num = 82;

    while (1) {
        do {
            int digit = num % 10;
            sum += digit * digit;
            num /= 10;
        } while (num != 0);
        if (sum == 1) {
            printf("happy");
            break;
        } else if (sum < 10) {
            printf("not happy");
            break;
        }
          num = sum;
          sum = 0;
    }