diff --git a/133_clone_graph/Makefile b/133_clone_graph/Makefile
new file mode 100644
index 0000000..4e700dc
--- /dev/null
+++ b/133_clone_graph/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test clone_graph.c
diff --git a/133_clone_graph/clone_graph.c b/133_clone_graph/clone_graph.c
new file mode 100644
index 0000000..cea7f4d
--- /dev/null
+++ b/133_clone_graph/clone_graph.c
@@ -0,0 +1,139 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct hlist_node;
+
+struct hlist_head {
+    struct hlist_node *first;
+};
+
+struct hlist_node {
+    struct hlist_node *next, **pprev;
+};
+
+static inline void INIT_HLIST_HEAD(struct hlist_head *h) {
+    h->first = NULL;
+}
+
+static inline void INIT_HLIST_NODE(struct hlist_node *n) {
+    n->next = NULL;
+    n->pprev = NULL;
+}
+
+static inline int hlist_empty(struct hlist_head *h) {
+    return !h->first;
+}
+
+static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
+{
+    if (h->first != NULL) {
+        h->first->pprev = &n->next;
+    }
+    n->next = h->first;
+    n->pprev = &h->first;
+    h->first = n;
+}
+
+static inline void hlist_del(struct hlist_node *n)
+{
+    struct hlist_node *next = n->next;
+    struct hlist_node **pprev = n->pprev;
+    *pprev = next;
+    if (next != NULL) {
+        next->pprev = pprev;
+    }
+}
+
+#define container_of(ptr, type, member) \
+    ((type *)((char *)(ptr) - (size_t)&(((type *)0)->member)))
+
+#define list_entry(ptr, type, member) \
+    container_of(ptr, type, member)
+
+#define hlist_for_each(pos, head) \
+    for (pos = (head)->first; pos; pos = pos->next)
+
+#define hlist_for_each_safe(pos, n, head) \
+    for (pos = (head)->first; pos && ({ n = pos->next; true; }); pos = n)
+
+#define NEIGHBORS_MAX_SIZE 100
+
+struct UndirectedGraphNode {
+    int label;
+    struct UndirectedGraphNode *neighbors[NEIGHBORS_MAX_SIZE];
+    int neighborsCount;
+};
+
+struct label_node {
+    struct UndirectedGraphNode *gn;
+    struct hlist_node node;
+};
+
+static struct UndirectedGraphNode *find(int label, int size, struct hlist_head *heads)
+{
+    int hash = (label < 0 ? -label : label) % size;
+    struct hlist_node *p;
+    hlist_for_each(p, &heads[hash]) {
+        struct label_node *ln = list_entry(p, struct label_node, node);
+        if (ln->gn->label == label) {
+            return ln->gn;
+        }
+    }
+    return NULL;
+}
+
+static struct UndirectedGraphNode *recursive_clone(struct UndirectedGraphNode *graph, struct hlist_head *heads, int size)
+{
+    if (graph == NULL) {
+        return NULL;
+    }
+
+    struct UndirectedGraphNode *node = find(graph->label, size, heads);
+    if (node != NULL) {
+        return node;
+    }
+
+    node = malloc(sizeof(*node));
+    node->label = graph->label;
+    node->neighborsCount = graph->neighborsCount;
+    struct label_node *ln = malloc(sizeof(*ln));
+    ln->gn = node;
+    int hash = (node->label < 0 ? -node->label : node->label) % size;
+    hlist_add_head(&ln->node, &heads[hash]);
+
+    int i;
+    for (i = 0; i < node->neighborsCount; i++) {
+        node->neighbors[i] = recursive_clone(graph->neighbors[i], heads, size);
+    }
+
+    return node;
+}
+
+static struct UndirectedGraphNode *cloneGraph(struct UndirectedGraphNode *graph)
+{
+    int i, cap = 1000;
+    struct hlist_head *heads = malloc(cap * sizeof(*heads));
+    for (i = 0; i < cap; i++) {
+        INIT_HLIST_HEAD(&heads[i]);
+    }
+
+    return recursive_clone(graph, heads, cap);
+}
+
+int main(void)
+{
+    struct UndirectedGraphNode n0, n1, n2;
+    n0.label = 0;
+    n1.label = 1;
+    n2.label = 2;
+    n0.neighborsCount = 2;
+    n1.neighborsCount = 1;
+    n2.neighborsCount = 1;
+    n0.neighbors[0] = &n1;
+    n0.neighbors[1] = &n2;
+    n1.neighbors[0] = &n2;
+    n2.neighbors[0] = &n2;
+
+    struct UndirectedGraphNode *res = cloneGraph(&n0);
+    return 0;
+}
diff --git a/134_gas_station/Makefile b/134_gas_station/Makefile
new file mode 100644
index 0000000..f2ca4c0
--- /dev/null
+++ b/134_gas_station/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test gas_station.c
diff --git a/134_gas_station/gas_station.c b/134_gas_station/gas_station.c
new file mode 100644
index 0000000..f9e1641
--- /dev/null
+++ b/134_gas_station/gas_station.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+static int canCompleteCircuit(int* gas, int gasSize, int* cost, int costSize)
+{
+    int i, j, store = 0, start = -1;
+    for (i = 0; i < gasSize; i++) {
+        if (start < 0) {
+            start = i;
+        }
+        store += gas[i] - cost[i];
+        if (store < 0) {
+            store = 0;
+            start = -1;
+        }
+    }
+    if (start > 0) {
+        for (i = 0; i < start; i++) {
+            store += gas[i] - cost[i];
+            if (store < 0) {
+                return -1;
+            }
+        }
+    }
+    return start;
+}
+
+int main(void)
+{
+    int gas[] = { 4 };
+    int cost[] = { 5 };
+    int count = sizeof(gas) / sizeof(*gas);
+    printf("%d\n", canCompleteCircuit(gas, count, cost, count));
+    return 0;
+}