107 lines
2.4 KiB
C
107 lines
2.4 KiB
C
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#include<stdlib.h>
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#include<stdio.h>
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#include<string.h>
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#include<stdbool.h>
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#include<unistd.h>
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struct antenna {
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char type;
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int xy[2];
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struct antenna *next;
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};
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void add_antenna(struct antenna *head, char type, int *xy)
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{
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// traverse list until last member
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while(head->next) head = head->next;
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// allocate and store ptr
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if (head->type) {
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head->next = malloc(sizeof(struct antenna));
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head = head->next;
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}
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head->type = type;
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head->xy[0] = xy[0];
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head->xy[1] = xy[1];
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head->next = 0;
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}
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int main ()
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{
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struct antenna *list = malloc(sizeof(struct antenna));
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list->type = '\0';
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// figure out data dimensions
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FILE *input = fopen("./input", "r");
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int width = 0;
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int height = 1;
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while (fgetc(input) != '\n') width++;
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for (char c = fgetc(input); c != EOF; c = fgetc(input)) {
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if (c == '\n')
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height++;
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}
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rewind(input);
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printf("Dimensions: %d x %d\n", width, height);
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// make 2d array
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char **grid = malloc(width * sizeof(char*));
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grid[0] = malloc(width * height);
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for (int i = 1; i < width; i++) {
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grid[i] = grid[0] + i * height;
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}
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// put the data in the array
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for (int i = 0; i < height; i++) {
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for (int j = 0; j < width; j++) {
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grid[j][i] = fgetc(input);
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if (grid[j][i] != '.') {
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// store antenna in list
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int xy[] = {j, i};
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add_antenna(list, grid[j][i], xy);
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printf("Antenna %c coords: %d/%d\n", grid[j][i], j, i);
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}
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}
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// skip newline
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fgetc(input);
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}
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fclose(input);
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struct antenna *current = list;
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struct antenna *other = list;
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// for each antenna in list
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while (current) {
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// find delta to other of same frequency
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while (other) {
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if (current->type == other->type && current != other) {
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int delta[2];
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delta[0] = other->xy[0] - current->xy[0];
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delta[1] = other->xy[1] - current->xy[1];
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// apply # to other + delta
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if (
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(other->xy[0] + delta[0]) >= 0 &&
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(other->xy[0] + delta[0]) < width &&
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(other->xy[1] + delta[1]) >= 0 &&
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(other->xy[1] + delta[1]) < height) {
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grid[other->xy[0] + delta[0]][other->xy[1] + delta[1]] = '#';
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}
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}
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other = other->next;
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}
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other = list;
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current = current->next;
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}
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// iterate through array again and sum it
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int sum_x = 0;
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for (int i = 0; i < height; i++) {
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for (int j = 0; j < width; j++) {
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if (grid[j][i] == '#')
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sum_x++;
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printf("%c", grid[j][i]);
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}
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printf("\n");
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}
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printf("total antinodes: %d\n", sum_x);
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}
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