Add 0496-next-greater-element-1.c

c/0496-next-greater-element-i.c

@@ -0,0 +1,92 @@
+#define INIT_HASH_SIZE 1024
+
+// Represent an element in a hash table.
+typedef struct Hash {
+ int key;
+ int value;
+ struct Hash *next;
+} Hash;
+
+// Use -1 as non-existed key,
+// as 0 <= nums1[i], nums2[i] <= 104
+Hash *InitHash() {
+ Hash *h = (Hash*)calloc(INIT_HASH_SIZE, sizeof(Hash));
+ assert(h);
+ for (int i = 0; i < INIT_HASH_SIZE; i++) {
+ h[i].key = -1;
+ }
+ return h;
+}
+
+Hash *NewHash(int key, int value) {
+ Hash *h = (Hash*)malloc(sizeof(Hash));
+ assert(h);
+ h->key = key;
+ h->value = value;
+ h->next = NULL;
+ return h;
+}
+
+int HashKey(int key) {
+ while(key < 0) key += INIT_HASH_SIZE;
+ return (key % INIT_HASH_SIZE);
+}
+
+void SetHash(Hash *root, int key, int value) {
+ assert(root);
+ Hash *h = &root[HashKey(key)];
+ if (h->key == -1) {
+ h->key = key;
+ h->value = value;
+ } else if (h->key == key) {
+ h->value = value;
+ } else {
+ while (h) {
+ if (h->key == key) {
+ h->value = value;
+ return;
+ } else if (!h->next) {
+ h->next = NewHash(key, value);
+ return;
+ }
+ h = h->next;
+ }
+ }
+}
+
+// If hash not round return -1 on purpose.
+int GetHash(Hash *root, int key) {
+ Hash *h = &root[HashKey(key)];
+ while(h) {
+ if (h->key == key) {
+ return h->value;
+ }
+ h = h->next;
+ }
+ return -1;
+}
+
+/**
+ * Note: The returned array must be malloced, assume caller calls free().
+ */
+int* nextGreaterElement(int* nums1, int nums1Size, int* nums2, int nums2Size, int* returnSize){
+ Hash *hash = InitHash();
+ int *res = (int*)malloc(nums1Size*sizeof(int));
+ int i, j;
+
+ for (i = 0; i < nums2Size; i++) {
+ for (j = i + 1; j < nums2Size; j++) {
+ if (nums2[j] > nums2[i]) {
+ SetHash(hash, nums2[i], nums2[j]);
+ break;
+ }
+ }
+ }
+
+ for (i = 0; i < nums1Size; i++) {
+ res[i] = GetHash(hash, nums1[i]);
+ }
+
+ *returnSize = nums1Size;
+ return res;
+}