98 lines
2 KiB
C
98 lines
2 KiB
C
#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <limits.h>
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bool in_state(unsigned int m, unsigned int state[m][m], unsigned int x) {
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for (int i = 0; i < m; ++i) {
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for (int j = i + 1; j < m; ++j) {
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if (state[i][j] == x) {
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return true;
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}
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}
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}
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return false;
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}
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void print_state(unsigned int m, unsigned int state[m][m]) {
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for (int i = 0; i < m; ++i) {
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for (int j = 0; j < m; ++j) {
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printf("%u ", state[i][j]);
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}
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printf("\n");
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}
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}
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void update_state(unsigned int m, unsigned int state[m][m], unsigned int *input,
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unsigned int k) {
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for (int i = k - m +1; i < k; ++i) {
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state[k % m][i % m] = input[i] + input[k];
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state[i % m][k % m] = input[i] + input[k];
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}
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}
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int main(int argc, char *argv[]) {
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if (argc < 3) {
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printf("Usage: %s <input file> <preamble size>\n", argv[0]);
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return 0;
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}
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FILE *fp = fopen(argv[1], "r");
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if (fp == NULL) {
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printf("Could not open file %s\n", argv[1]);
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return 1;
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}
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unsigned int m;
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sscanf(argv[2], "%d", &m);
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unsigned int input[1024] = {0};
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unsigned int n = 0;
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unsigned int d;
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while (fscanf(fp, "%d\n", &d) == 1) {
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input[n] = d;
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n++;
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}
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fclose(fp);
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// Part 1
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unsigned int state[m][m];
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for (int i = 0; i < m; ++i) {
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for (int j = 0; j < m; ++j) {
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if (i != j) {
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state[i][j] = input[i] + input[j];
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} else {
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state[i][j] = 0;
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}
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}
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}
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unsigned int k = m;
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while (in_state(m, state, input[k])) {
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update_state(m, state, input, k);
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k++;
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}
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printf("%u\n", input[k]);
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// Part 2
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unsigned int invalid_number = input[k];
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for (int width = 2; width < n; ++width) {
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for (int i = 0; i < n - width; ++i) {
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unsigned int sum = 0;
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unsigned int min = UINT_MAX;
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unsigned int max = 0;
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for (int j = 0; j < width; ++j) {
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sum += input[i + j];
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min = (input[i + j] < min) ? input[i + j] : min;
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max = (input[i + j] > max) ? input[i + j] : max;
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}
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if (sum == invalid_number) {
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printf("%u\n", min + max);
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return 0;
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}
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}
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}
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return 0;
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}
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