Day1

day1/c/day1.c

@@ -0,0 +1,64 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define LINE_MAX 64
+#define LIST_MAX 1024
+#define abs(a) (a) < 0 ? -(a) : (a);
+
+int cmp(const void*, const void*);
+
+int main() {
+    char *p, *buf, c;
+    int left, right, *left_list, *right_list, i = 0;
+
+    buf = calloc(LINE_MAX, sizeof(char));
+    p = buf;
+    left_list = calloc(LIST_MAX, sizeof(*left_list));
+    right_list = calloc(LIST_MAX, sizeof(*right_list));
+
+    while ((c = getchar()) != EOF) {
+        *p++ = c;
+        if (c == '\n') {
+            *p = '\0';
+            sscanf(buf, "%i %i", &left, &right);
+            left_list[i] = left;
+            right_list[i] = right;
+            i++;
+            memset(buf, 0, LINE_MAX);
+            p = buf;
+        }
+    }
+
+    free(buf);
+
+    qsort(left_list, i, sizeof(*left_list), cmp);
+    qsort(right_list, i, sizeof(*right_list), cmp);
+
+    int sum = 0;
+    for (int j = 0; j < i; j++) {
+        sum += abs(left_list[j] - right_list[j]);
+    }
+
+    int similarity = 0;
+
+    for (int j = 0; j < i; j++) {
+        int count = 0;
+        for (int k = 0; k < i; k++) {
+            if (left_list[j] == right_list[k]) {
+                count++;
+            }
+        }
+        similarity += left_list[j] * count;
+    }
+
+    free(left_list);
+    free(right_list);
+
+    printf("%i\n", sum);
+    printf("%i\n", similarity);
+}
+
+int cmp(const void* a, const void* b) {
+    return *(int*)a - *(int*)b;
+}