I have been trying to solve a problem where i needed to find the sum of the minimum of all the subarrays of an array. If someone know of an O(N) algorithm to such problem. Thanks.

I was interested in practising more on problems Div2 C and Div2 D, But such problems where they don't depend on any specific algorithms: dp, binary search, graph, tree,....etc rather on problem solving skills where the difficulty is in the apprehending the solution itself. also problems which depend on creating certain permutations or matrices that specifies certain conditions.

any resources related will be welcomed too. If you can recommend any please, Thanks a lot :D