diff --git a/128_longest_consecutive_sequence/Makefile b/128_longest_consecutive_sequence/Makefile
new file mode 100644
index 0000000..7b3d506
--- /dev/null
+++ b/128_longest_consecutive_sequence/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test consec_seq.c
diff --git a/128_longest_consecutive_sequence/consec_seq.c b/128_longest_consecutive_sequence/consec_seq.c
new file mode 100644
index 0000000..a290d5c
--- /dev/null
+++ b/128_longest_consecutive_sequence/consec_seq.c
@@ -0,0 +1,132 @@
+#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)
+
+struct seq_node {
+    int num;
+    struct hlist_node node;
+};
+
+static struct seq_node *find(int num, int size, struct hlist_head *heads)
+{
+    int hash = num < 0 ? -num % size : num % size;
+    struct hlist_node *pos;
+    hlist_for_each(pos, &heads[hash]) {
+        struct seq_node *node = list_entry(pos, struct seq_node, node);
+        if (node->num == num) {
+            return node;
+        }
+    }
+    return NULL;
+}
+
+static int longestConsecutive(int* nums, int numsSize) {
+    int i, hash, length = 0;
+    struct seq_node *node;
+    struct hlist_head *heads = malloc(numsSize * sizeof(*heads));
+
+    for (i = 0; i < numsSize; i++) {
+        INIT_HLIST_HEAD(&heads[i]);
+    }
+
+    for (i = 0; i < numsSize; i++) {
+        if (!find(nums[i], numsSize, heads)) {
+            hash = nums[i] < 0 ? -nums[i] % numsSize : nums[i] % numsSize;
+            node = malloc(sizeof(*node));
+            node->num = nums[i];
+            hlist_add_head(&node->node, &heads[hash]);
+        }
+    }
+
+    for (i = 0; i < numsSize; i++) {
+        int len = 0;
+        int num;
+        node = find(nums[i], numsSize, heads);
+        while (node != NULL) {
+            len++;
+            num = node->num;
+            hlist_del(&node->node);
+
+            int left = num;
+            while ((node = find(--left, numsSize, heads)) != NULL) {
+                len++;
+                hlist_del(&node->node);
+            }
+
+            int right = num;
+            while ((node = find(++right, numsSize, heads)) != NULL) {
+                len++;
+                hlist_del(&node->node);
+            }
+
+            length = len > length ? len : length;
+        }
+    }
+
+    return length;
+}
+
+int main(int argc, char **argv)
+{
+    int i, size = argc - 1;
+    int *nums = malloc(size * sizeof(int));
+    for (i = 0; i < size; i++) {
+        nums[i] = atoi(argv[i + 1]);
+    }
+    printf("%d\n", longestConsecutive(nums, size));
+    return 0;
+}