how to approach this SUMNUM Problem - CodeChef problem.
i used next_permutation which is available in c++ but that gave me TLE .so now how should i solve this
I think there is problem in test cases of 2nd subtask because my code is showing WA rather than TLE. I have check other codes of coders and i found that no one got 100 till now.
I have just changed your code a little bit and make the complexity O(N) per test case. You can see my solution here.
My changes is simple. I just found a repeated pattern in sum[] array, which can easily be calculated without using next_permutation() function. I am not explaining it as i want that you should try first, after that if you wouldn’t reach the solution then comment here. I will explain it for you.
But at last i think 2nd subtask have some problem.
This problem almost drove me nuts tbh. I gave up after 10 mins of brainstorming.
If you still doubt then you can see this article. But it’s only for distinct digits. Sum of all numbers that can be formed with permutations of n digits - GeeksforGeeks