118 lines
No EOL
3.3 KiB
C
118 lines
No EOL
3.3 KiB
C
#include "include/day1_input.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <inttypes.h>
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struct list_ctx {
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u_int32_t* list;
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size_t list_len;
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};
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struct list_pair {
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struct list_ctx *left;
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struct list_ctx *right;
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};
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struct list_pair *parse_input_day1() {
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struct list_pair *ctx = malloc(sizeof(struct list_pair));
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ctx->left = malloc(sizeof(struct list_ctx));
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ctx->left->list = malloc(1000 * sizeof(u_int32_t));
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ctx->left->list_len = 1000;
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ctx->right = malloc(sizeof(struct list_ctx));
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ctx->right->list = malloc(1000 * sizeof(u_int32_t));
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ctx->right->list_len = 1000;
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int list_i = 0;
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int list_buf_len = 0;
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char *list_buf = NULL;
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for(int i = 0; i < input_day1_txt_len; i++) {
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char c = input_day1_txt[i];
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switch(c) {
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case ' ':
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if (list_buf_len) {
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ctx->left->list[list_i] = strtoul(list_buf, NULL, 10);
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list_buf_len = 0;
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free(list_buf);
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list_buf = NULL;
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};
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break;
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case '\n': {
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ctx->right->list[list_i] = strtoul(list_buf, NULL, 10);
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list_i++;
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list_buf_len = 0;
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free(list_buf);
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list_buf = NULL;
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break;
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}
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default: {
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list_buf_len++;
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list_buf = realloc(list_buf, list_buf_len * sizeof(char));
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list_buf[list_buf_len-1] = c;
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}
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}
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}
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return ctx;
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}
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void selection_sort(struct list_ctx *ctx) {
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for(int start_i = 0; start_i < ctx->list_len; start_i++) {
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size_t min_i = start_i;
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for (size_t i = start_i + 1; i < ctx->list_len; i++) {
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if (ctx->list[i] < ctx->list[min_i]) {
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min_i = i;
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}
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}
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if (min_i != start_i) {
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u_int32_t t = ctx->list[start_i];
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ctx->list[start_i] = ctx->list[min_i];
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ctx->list[min_i] = t;
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}
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}
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}
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char *day_1_part_1() {
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struct list_pair *pair = parse_input_day1();
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selection_sort(pair->left);
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selection_sort(pair->right);
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int total = 0;
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for(int i = 0; i < 1000; i++)
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total += pair->left->list[i] > pair->right->list[i] ? pair->left->list[i] - pair->right->list[i] : pair->right->list[i] - pair->left->list[i];
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free(pair->left->list);
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free(pair->right->list);
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free(pair->left);
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free(pair->right);
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free(pair);
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int len = snprintf(NULL, 0, "%d", total);
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char *total_str = malloc(len +1);
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snprintf(total_str, len, "%d", total);
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return total_str;
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}
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char *day_1_part_2() {
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struct list_pair *pair = parse_input_day1();
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int total = 0;
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// TODO: do not the O(n^2)
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for(int left_i = 0; left_i < pair->left->list_len; left_i++) {
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int c = 0;
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for(int right_i = 0; right_i < pair->right->list_len; right_i++)
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if(pair->left->list[left_i] == pair->right->list[right_i]) c++;
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total += c*pair->left->list[left_i];
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}
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free(pair->left->list);
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free(pair->right->list);
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free(pair->left);
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free(pair->right);
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free(pair);
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int len = snprintf(NULL, 0, "%d", total) + 1;
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char *total_str = malloc(len);
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snprintf(total_str, len, "%d", total);
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return total_str;
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} |