Tips to solve the DSA questions by recognizing their pattern.

Tips to solve the DSA questions by recognizing their pattern.

If given a linked list then

✒ Two pointers

If the input array is sorted then

✒ Binary search

✒ Two pointers

If asked for all permutations/subsets then

✒ Backtracking

If given a tree or a graph then

✒ DFS

✒ BFS

If recursion is banned then

✒ Stack

If must solve in-place then

✒ Swap corresponding values

✒ Store one or more different values in the same pointer

If asked for maximum/minimum subarray/subset/options then

✒ Dynamic programming

If asked for top/least K items then

✒ Heap

If asked for common strings then

✒ Map

✒ Trie

General Tips

✒ Map/Set for O(1) time & O(n) space

✒ Sort input for O(nlogn) time and O(1) space