Jan 10 - Daily Programming Diary

6:30

Starting a bit early today. I was looking at the <Navbar /> yesterday and thought the performance on first reload could be improved by using useEffect instead of the currently used location listener. Voila! It worked.

See, I can do UI fixes as well 🤷‍♂️

8:00

I was exploring the source code and figured out 2 major things -

• The react router only works with <Link /> component. The <a/> tags don't go well when working with SPAs.
• I don't know react.

setTimeout(() => resumeWork(), 2 * 1000 * 60 * 60);

10:05

Started with the Crio bytes. Since I already knew the basics of HTTP, REST, Linux, and EC2, I was able to zoom through the modules pretty quickly.

14:30

Starting with today's Leetcode Challenge. At first I wasn't able to understand the question. I thought I had to calculate the minimum cost of creating the sorted array which got me confused. After reading it for the nth time, I figured that the elements have to be inserted in an orderly manner.

15:00

It's been half an hour and the code I wrote to do the calculation is giving TLE, and I get it. The implementation is taking O(n^2) time to calculate the prefix sum. I have no idea so I'm gonna take a look at the hint.

15:20

So I studied about BIT aka Binary Indexed Tree, which calculates prefix sum in O(logn) time so the overall complexity of my program will go down to O(nlogn).

16:00

Done with the code. Wow! New gun in my arsenal.

Copycreate-sorted-array-through-instructions.cpp: copy code to clipboard
1int bit[100002];
2
3// Find prefix sum of a number
4int prefixSum(int num) {
5    int ans = 0;
6    for (int i = num; i > 0; i -= (i & -i)) {
7        ans += bit[i];
8    }
9    return ans;
10}
11
12// Update the prefix sum values
13int update(int num) {
14    for (int i = num; i <= 100001; i += (i & -i)) {
15        bit[i] += 1;
16    }
17    return 0;
18}
19
20int createSortedArray(vector<int> &inst) {
21    int ans = 0;
22    for (int i = 0; i < inst.size(); i++) {
23        ans += min(prefixSum(inst[i] - 1), i - prefixSum(inst[i]));
24        ans %= 1000000007;
25        update(inst[i]);
26    }
27    return ans;
28}

Again, no Go for this question. I'm just gonna put Go on hold for now unless I have some work on the back-end.

break;

18:00

Attending the Crio event now for REST byte.

19:00

To be honest, after having developed a few production-ready APIs, I didn't learn anything new in the session but I guess I'll complete the byte and see what round 2 has for me.

22:30

I started with building the Raahee server and made a boilerplate. Took some time to get the modules ready. Will be working on the database models now.

23:00

Been writing models for the last 30 minutes and there are some issues. The conventions used in the document are inconsistent. imageUrl and imageurl in different collections. It's a bit frustrating to actually look for these things when back-end is generally the first thing built.

23:30

I'm tired now and will continue tomorrow. Will possibly work on the authentication and basic doc creation for events and such.

Okay Bye

EOD Checklist

• Leetcode January Challenge
• Raahee (Just attended the meeting)
• This blog