Back Tracking and Recursion good questions

(1) Word Search II (leetcode 212)
(2) Word Pattern II (leetcode 291)
(3) Word Ladder II (leetcode 126)
(4) Restore IP Address (leetcode 93)
(5) Permutation II (leetcode 47) I (leetcode 46) subset(leetcode 78) - both back tracing & recursion
(6) Generalized Abbreviation (leetcode 320)
(7) Combination Sum II (leetcode 216)
(8) Strobogrammatic Number II (leetcode 247)
(9) longest increasing Path in a Matrix (leetcode 329)
(10) word break (leetcode 139) use both backtracking and DP
(11) Expression add operators (leetcode 282)