82 lines
1.6 KiB
C
82 lines
1.6 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#include <inttypes.h>
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#include <stdbool.h>
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#define DIGITS (6)
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#define BASE_TEN (100000)
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uint32_t* get_digits(uint32_t n) {
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uint32_t* r = malloc(sizeof(uint32_t) * DIGITS);
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uint32_t base = BASE_TEN;
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for (size_t i = 0; i < DIGITS; i++) {
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r[i] = n / base;
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n = n % base;
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base /= 10;
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}
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return r;
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}
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uint32_t* get_power_four_lookup() {
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uint32_t* r = malloc(sizeof(uint32_t) * 10);
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r[0] = 0;
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r[1] = 1;
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r[2] = 2 * 2 * 2 * 2;
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r[3] = 3 * 3 * 3 * 3;
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r[4] = 4 * 4 * 4 * 4;
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r[5] = 5 * 5 * 5 * 5;
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r[6] = 6 * 6 * 6 * 6;
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r[7] = 7 * 7 * 7 * 7;
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r[8] = 8 * 8 * 8 * 8;
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r[9] = 9 * 9 * 9 * 9;
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return r;
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}
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uint32_t* get_power_five_lookup() {
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uint32_t* r = malloc(sizeof(uint32_t) * 10);
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r[0] = 0;
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r[1] = 1;
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r[2] = 2 * 2 * 2 * 2 * 2;
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r[3] = 3 * 3 * 3 * 3 * 3;
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r[4] = 4 * 4 * 4 * 4 * 4;
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r[5] = 5 * 5 * 5 * 5 * 5;
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r[6] = 6 * 6 * 6 * 6 * 6;
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r[7] = 7 * 7 * 7 * 7 * 7;
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r[8] = 8 * 8 * 8 * 8 * 8;
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r[9] = 9 * 9 * 9 * 9 * 9;
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return r;
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}
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bool is_representable(uint32_t number, uint32_t* lookup) {
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uint32_t* digits = get_digits(number);
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uint32_t digit_sum = 0;
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for (size_t i = 0; i < DIGITS; i++)
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digit_sum += lookup[digits[i]];
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free(digits);
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if (number == digit_sum)
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return true;
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return false;
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}
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void print_digits(uint32_t* digits) {
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for (size_t i = 0; i < DIGITS; i++) {
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printf("%u", digits[i]);
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}
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}
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int main(int argn, char** argv) {
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uint32_t* lookup = get_power_five_lookup();
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uint32_t sum = 0;
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for (uint32_t n = 10; n < 300000; n++)
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if (is_representable(n, lookup)) {
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printf("%u\n", n);
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sum += n;
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}
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printf("Sum: %d\n", sum);
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free(lookup);
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return 0;
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}
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