跳表（附带调试函数，未验证正确性）

Skip-List.cpp

@@ -0,0 +1,130 @@
+#include <cstdio>
+#include <cstdlib>
+
+#define NIL 0
+#define LAYER_COUNT 20
+#define NODE_COUNT 100000
+
+using namespace std;
+
+struct node
+{
+	int id, value;
+	node *next, *lower;
+	node();
+};
+
+node::node() : next(NIL) { }
+
+node *head[LAYER_COUNT];
+
+void init()
+{
+	head[0] = new node;
+	for (int i = 1; i < LAYER_COUNT; i++)
+	{
+		head[i] = new node;
+		head[i]->lower = head[i - 1];
+	}
+}
+
+void insert(int id, int value)
+{
+	int k = 0;
+	while ((rand() & 1) == 0)
+	{
+		k++;
+	}
+	node *prev = head[k], *cur = head[k], *upper = NIL;
+	for (; k >= 0; k--)
+	{
+		while (cur != NIL && cur->id < id)
+		{
+			prev = cur;
+			cur = cur->next;
+		}
+		node *o = new node;
+		o->next = cur;
+		o->id = id;
+		o->value = value;
+		prev->next = o;
+		prev = prev->lower;
+		cur = prev;
+		if (upper != NIL)
+		{
+			upper->lower = o;
+		}
+		upper = o;
+	}
+}
+
+int find(int id)
+{
+	node *prev, *cur = head[LAYER_COUNT - 1];
+	for (int k = LAYER_COUNT - 1; k >= 0; k--)
+	{
+		while (cur != NIL && cur->id < id)
+		{
+			prev = cur;
+			cur = cur->next;
+		}
+		if (cur != NIL && cur->id == id)
+		{
+			return cur->value;
+		}
+		else
+		{
+			prev = prev->lower;
+			cur = prev;
+		}
+	}
+	return -1;
+}
+
+void debug()
+{
+	for (int i = 5; i >= 0; i--)
+	{
+		node *cur = head[i];
+		printf("head[%d]", i);
+		while (cur != NIL)
+		{
+			printf(" -> (%d, %d)", cur->id, cur->value);
+			cur = cur->next;
+		}
+		printf("\n");
+	}
+}
+
+int main()
+{
+	int in, id, value;
+	init();
+	while (true)
+	{
+		scanf("%d", &in);
+		if (in == 1)
+		{
+			scanf("%d%d", &id, &value);
+			insert(id, value);
+		}
+		else if (in == 2)
+		{
+			scanf("%d", &id);
+			printf("%d\n", find(id));
+		}
+		else if (in == 4)
+		{
+			debug();
+		}
+		else if (in == 0)
+		{
+			return 0;
+		}
+		else
+		{
+			printf("No such command!\n");
+		}
+	}
+	return 0;
+}