07: Solve in C

07/solution.c

@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct entry {
+    char *name;
+    int isdir;
+    size_t size;
+    struct entry **entries;
+    size_t n_entries;
+    struct entry *parent;
+} entry;
+
+entry *findent(entry *e, int isdir, const char *name) {
+    for (size_t i = 0; i < e->n_entries; i++) {
+        if (e->entries[i]->isdir == isdir)
+            if (!strcmp(e->entries[i]->name, name))
+                return e->entries[i];
+    }
+
+    return NULL;
+}
+
+entry *addent(entry *parent, int isdir, const char *name) {
+    if (parent->n_entries)
+        parent->entries = realloc(parent->entries, ++(parent->n_entries) * sizeof(entry*));
+    else
+        parent->entries = malloc(++(parent->n_entries) * sizeof(entry*));
+
+    entry *e = parent->entries[parent->n_entries - 1] = calloc(1, sizeof(entry));
+    e->isdir = isdir;
+    e->name = malloc(strlen(name) + 1);
+    strcpy(e->name, name);
+    e->parent = parent;
+
+    return e;
+}
+
+int main(void) {
+    char l[64];
+    entry *root = calloc(1, sizeof(entry));
+    root->isdir++;
+    entry *current;
+    size_t S = 0, G = 0, required = 0;
+
+    while (fgets(l, 64, stdin)) {
+        l[strlen(l) - 1] = '\0';
+        if (l[0] == '$') {
+            if (l[2] == 'c')
+                if (l[5] == '/')
+                    current = root;
+                else if (l[5] == '.')
+                    current = current->parent;
+                else
+                    current = findent(current, 1, l + 5);
+        } else if (l[0] == 'd') {
+            if (!findent(current, 1, l + 4))
+                addent(current, 1, l + 4);
+        } else {
+            char *p;
+            size_t sz = strtoul(l, &p, 10);
+            entry *f = addent(current, 0, p + 1);
+            f->size = sz;
+            for (f = current; f->parent; f = f->parent)
+                f->size += sz;
+            f->size += sz;
+        }
+    }
+
+    current = root;
+    required = 30000000UL - (70000000UL - root->size);
+    do {
+        if (current->n_entries) {
+            current->n_entries--;
+            current = (current->entries++)[0];
+        } else {
+            if (current->isdir)
+                if (current->size < 100000)
+                    S += current->size;
+                else if (current->size >= required && (current->size < G || !G))
+                    G = current->size;
+
+            current = current->parent;
+        }
+    } while (current);
+
+    printf("Silver: %lu\nGold: %lu\n", S, G);
+}