https://leetcode.com/problems/freedom-trail/description/

Min steps to produce key by rotating ring #hard #dynamic_programming #recursion #hash_map

https://leetcode.com/problems/count-of-interesting-subarrays/description/

Subarrays, count a[i]%m=k is c%m=k #medium #hash_map

Dominoes pairs #easy #hash

https://leetcode.com/problems/number-of-equivalent-domino-pairs/description/