C语言 | Leetcode C语言题解之第446题等差数列划分II-子序列

题目：

题解：

#define HASH_FIND_LONG(head, findint, out) HASH_FIND(hh, head, findint, sizeof(long), out)
#define HASH_ADD_LONG(head, intfield, add) HASH_ADD(hh, head, intfield, sizeof(long), add)struct HashTable {long key;int val;UT_hash_handle hh;
};int query(struct HashTable** HashTable, long ikey) {struct HashTable* tmp;HASH_FIND_LONG(*HashTable, &ikey, tmp);return tmp == NULL ? 0 : tmp->val;
}void add(struct HashTable** HashTable, long ikey, int ival) {struct HashTable* tmp;HASH_FIND_LONG(*HashTable, &ikey, tmp);if (tmp == NULL) {tmp = malloc(sizeof(struct HashTable));tmp->key = ikey, tmp->val = ival;HASH_ADD_LONG(*HashTable, key, tmp);} else {tmp->val += ival;}
}int numberOfArithmeticSlices(int* nums, int numsSize) {int ans = 0;struct HashTable* hashTable[numsSize];memset(hashTable, 0, sizeof(hashTable));for (int i = 0; i < numsSize; ++i) {for (int j = 0; j < i; ++j) {long long d = 1LL * nums[i] - nums[j];int cnt = query(&hashTable[j], d);ans += cnt;add(&hashTable[i], d, cnt + 1);}}return ans;
}