#include <cstdio> #define FMAX (9*9 * 19) int f(unsigned long long n) { int res = 0; while (n) { int d = n % 10; res += (d * d); n /= 10; } return res; } int main() { unsigned long long k, a, b; scanf("%llu%llu%llu", &k, &a, &b); // k * f(n) = n; // f(n) <= FMAX // f(n) = k/n // k/n <= FMAX int res = 0; for (int i = 1; i <= FMAX; ++i) { unsigned long long n = i * k; if (n > b) break; if (n >= a && f(n) == i) { // printf("< %llu\n", n); ++res; } } printf("%d\n", res); }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | #include <cstdio> #define FMAX (9*9 * 19) int f(unsigned long long n) { int res = 0; while (n) { int d = n % 10; res += (d * d); n /= 10; } return res; } int main() { unsigned long long k, a, b; scanf("%llu%llu%llu", &k, &a, &b); // k * f(n) = n; // f(n) <= FMAX // f(n) = k/n // k/n <= FMAX int res = 0; for (int i = 1; i <= FMAX; ++i) { unsigned long long n = i * k; if (n > b) break; if (n >= a && f(n) == i) { // printf("< %llu\n", n); ++res; } } printf("%d\n", res); } |