Added heap skewed.

current/algorithms/heap_skewed.c

@@ -0,0 +1,111 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+typedef struct _node {
+  struct _node* left;
+  struct _node* right;
+  long key;
+} node;
+
+void visit_node_in_order(node* q, void (*callback)(node *)) {
+  if (!q) {
+    return;
+  }
+
+  visit_node_in_order(q->left, callback);
+  callback(q);
+  visit_node_in_order(q->right, callback);
+}
+
+void visit_node_post_order(node *q, void (*callback)(node *)) {
+  if (!q) {
+    return;
+  }
+
+  visit_node_post_order(q->left, callback);
+  visit_node_post_order(q->right, callback);
+  callback(q);
+}
+
+void node_destroy(node *q) {
+  void (*func)(node *) = (void (*)(node *))free;
+  visit_node_post_order(q, func);
+}
+
+node* node_union(node* l, node* r) {
+  if (!l) {
+    return r;
+  }
+
+  if (!r) {
+    return l;
+  }
+
+  node* res;
+
+  if (l->key >= r->key) {
+    res = l;
+    res->right = node_union(l->right, r);
+  } else {
+    res = r;
+    res->right = node_union(r->right, l);
+  }
+
+  node *q = res->left;
+  res->left = res->right;
+  res->right = q;
+
+  return res;
+}
+
+const int MAX_BUFFER = 0x1000;
+
+int main() {
+  char cmd[MAX_BUFFER];
+  node *q = NULL;
+  while (1) {
+    fgets(cmd, MAX_BUFFER, stdin);
+    printf("Got command %s\n", cmd);
+
+    if (strlen(cmd) == 0 || cmd[0] == '\n') {
+      printf("Finished reading\n");
+      break;
+    } else if (memcmp(cmd, "ADD", 3) == 0) {
+      // handle command add
+      int x = atoi(cmd + 4);
+      node *el = (node *)malloc(sizeof(node));
+      el->left = NULL;
+      el->right = NULL;
+      el->key = x;
+  
+      if (q) {
+        q = node_union(q, el);
+      } else {
+        q = el;
+      }
+
+      printf("Added number: %d\n", x);
+  
+    } else if (memcmp(cmd, "DEL", 3) == 0) {
+      // handle command del
+      if (!q) {
+        fprintf(stderr, "There is nothing to delete - heap is empty\n");
+        continue;
+      }
+      long key = q->key;
+      q = node_union(q->left, q->right);
+      printf("Removed element: %d\n", key);
+    } else {
+      // handle unknown command
+      fprintf(stderr, "Got unknown command %s\n", cmd);
+    }
+
+  }
+
+  if (!q) {
+    node_destroy(q);
+  }
+
+  return 0;
+}