Hey everyone,

I’m looking for an accountability partner to stay consistent and motivated while preparing for Data Structures and Algorithms (DSA). I’m a software engineer with a goal of improving my problem-solving skills, staying disciplined, and preparing for coding interviews.

therefore its implementations would be data structures also?for ex could we describe quick find as a algorithm or data structure?

A coach wants to give gold coins to the participants based on their performance. Each participant can see his coins, participate adjacent to him and adjacent to them. I.e, for ith index, participant see coins given from i-2 to i+2. Find the sum of minimum coins given. Eg input: [35, 14, 42, 44, 39] Output: 6 -> [1,0,2,3,0] Input: [26, 10, 45, 35, 38, 41, 16] Output: 14 -> [1, 0, 4, 2, 3, 4, 0]

There's a minimum chocolate program on geeksforgeeks, but in that only i-1, i, and i+1 are visible and I am not getting the same after applying that idea.

I know it is a frequently asked question here but i would like to know how to approach DSA questions as a noobie. I was thinking of starting to watch Greg Hogg DSA playlist in order from arrays to dynamic programming to learn the concepts and then I solve the neetcode 150.

So here are my questions:

1. What are the ways to solve the neetcode 150 questions on your own and not look into the solution everytime.
2. Should I solve the questions on difficulty first or go by the order of pattern in neetcode 150.

You can also share your approach and how you went on solving the neetcode 150 and prep for the interviews !

Hey everyone,

I'm in a challenging situation with a corrupted-21.4GB\multiple MP4 video file(s), and this is actually a recurring problem for me. I could really use some advice on both recovering this file and preventing this issue in the future. Here's the situation:

• The Incident: My camera (Sony a7 III) unexpectedly shut down due to battery drain while recording a video. It had been recording for approximately 20-30 minutes.
• File Details:
  • The resulting MP4 file is 21.4 GB in size, as reported by Windows.
  • A healthy file from the same camera, same settings, and a similar duration (30 minutes) is also around 20 GB.
  • When I open the corrupted file in a hex editor, approximately the first quarter contains data. But after that it's a long sequence of zeros.
  • Compression Test: I tried compressing the 21.4 GB file. The resulting compressed file is only 1.45 GB. I have another corrupted file from a separate incident (also a Sony a7 III battery failure) that is 18.1 GB. When compressed, it shrinks down to 12.7 GB.
• MP4 Structure:
  • Using a tool to inspect the MP4 boxes, I've found that the corrupted file is missing the moov atom (movie header). it has it but not all of it or maybe corrupted?
  • It has an ftyp (file type) box, a uuid (user-defined metadata) box, and an mdat (media data) box. The mdat box is partially present.
  • The corrupted file has eight occurrences of the text "moov" scattered throughout, whereas a healthy file from the same camera has many more(130). These are likely incomplete attempts by the camera to write the moov atom before it died.
• What I've Tried (Extensive List):
  • I've tried numerous video repair tools, including specialized ones, but none have been able to fix the file or even recognize it.
  • I can likely extract the first portion using a hex editor and FFmpeg.
  • untrunc*:** This tool specifically designed for repairing truncated MP4/MOV files, recovered only about 1.2 minutes after a long processing time.
  • Important Note: I've recovered another similar corrupted file using untrunc in the past, but that file exhibited some stuttering in editing software.
  • FFmpeg Attempt: I tried using ffmpeg to repair the corrupted file by referencing the healthy file. The command appeared to succeed and created a new file, but the new file was simply an exact copy of the healthy reference file, not a repaired version of the corrupted file. Here's the commands I used:

​

      ffmpeg -i "corrupted.mp4" -i "reference.mp4" -map 0 -map 1:a -c copy "output.mp4"

*   [mov,mp4,m4a,3gp,3g2,mj2 @ 0000018fc82a77c0] moov atom not found
[in#0 @ 0000018fc824e080] Error opening input: Invalid data found when processing input
Error opening input file corrupted.mp4.
Error opening input files: Invalid data found when processing input]

      ffmpeg -f concat -safe 0 -i reference.txt -c copy repaired.mp4

*   [mov,mp4,m4a,3gp,3g2,mj2 @ 0000023917a24940] st: 0 edit list: 1 Missing key frame while searching for timestamp: 1001
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000023917a24940] st: 0 edit list 1 Cannot find an index entry before timestamp: 1001.
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000023917a24940] Auto-inserting h264_mp4toannexb bitstream filter
[concat @ 0000023917a1a800] Could not find codec parameters for stream 2 (Unknown: none): unknown codec
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
[aist#0:1/pcm_s16be @ 0000023917a2bcc0] Guessed Channel Layout: stereo
Input #0, concat, from 'reference.txt':
  Duration: N/A, start: 0.000000, bitrate: 97423 kb/s
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/bt709/arib-std-b67, progressive), 3840x2160 [SAR 1:1 DAR 16:9], 95887 kb/s, 29.97 fps, 29.97 tbr, 30k tbn
      Metadata:
        creation_time   : 2024-03-02T06:31:33.000000Z
        handler_name    : Video Media Handler
        vendor_id       : [0][0][0][0]
        encoder         : AVC Coding
  Stream #0:1(und): Audio: pcm_s16be (twos / 0x736F7774), 48000 Hz, stereo, s16, 1536 kb/s
      Metadata:
        creation_time   : 2024-03-02T06:31:33.000000Z
        handler_name    : Sound Media Handler
        vendor_id       : [0][0][0][0]
  Stream #0:2: Unknown: none
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Output #0, mp4, to 'repaired.mp4':
  Metadata:
    encoder         : Lavf61.6.100
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/bt709/arib-std-b67, progressive), 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 95887 kb/s, 29.97 fps, 29.97 tbr, 30k tbn
      Metadata:
        creation_time   : 2024-03-02T06:31:33.000000Z
        handler_name    : Video Media Handler
        vendor_id       : [0][0][0][0]
        encoder         : AVC Coding
  Stream #0:1(und): Audio: pcm_s16be (ipcm / 0x6D637069), 48000 Hz, stereo, s16, 1536 kb/s
      Metadata:
        creation_time   : 2024-03-02T06:31:33.000000Z
        handler_name    : Sound Media Handler
        vendor_id       : [0][0][0][0]
Press [q] to stop, [?] for help
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000023919b48d00] moov atom not foundrate=97423.8kbits/s speed=2.75x
[concat @ 0000023917a1a800] Impossible to open 'F:\\Ep09\\Dr.AzizTheGuestCam\\Corrupted.MP4'
[in#0/concat @ 0000023917a1a540] Error during demuxing: Invalid data found when processing input
[out#0/mp4 @ 00000239179fdd00] video:21688480KiB audio:347410KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 0.011147%
frame=55530 fps= 82 q=-1.0 Lsize=22038346KiB time=00:30:52.81 bitrate=97439.8kbits/s speed=2.75x

      Untrunc analyze

*   0:ftyp(28)
28:uuid(148)
176:mdat(23056088912)<--invalidlength
39575326:drmi(2571834061)<--invalidlength
55228345:sevc(985697276)<--invalidlength
68993972:devc(251968636)<--invalidlength
90592790:mean(4040971770)<--invalidlength
114142812:ctts(1061220881)<--invalidlength
132566741:avcp(2779720137)<--invalidlength
225447106:stz2(574867640)<--invalidlength
272654889:skip(2657341105)<--invalidlength
285303108:alac(3474901828)<--invalidlength
377561791:subs(3598836581)<--invalidlength
427353464:chap(2322845602)<--invalidlength
452152807:tmin(3439956571)<--invalidlength
491758484:dinf(1760677206)<--invalidlength
566016259:drmi(1893792058)<--invalidlength
588097258:mfhd(3925880677)<--invalidlength
589134677:stsc(1334861112)<--invalidlength
616521034:sawb(442924418)<--invalidlength
651095252:cslg(2092933789)<--invalidlength
702368685:sync(405995216)<--invalidlength
749739553:stco(2631111187)<--invalidlength
827587619:rtng(49796471)<--invalidlength
830615425:uuid(144315165)
835886132:ilst(3826227091)<--invalidlength
869564533:mvhd(3421007411)<--invalidlength
887130352:stsd(3622366377)<--invalidlength
921045363:elst(2779671353)<--invalidlength
943194122:dmax(4005550402)<--invalidlength
958080679:stsz(3741307762)<--invalidlength
974651206:gnre(2939107778)<--invalidlength
1007046387:iinf(3647882974)<--invalidlength
1043020069:devc(816307868)<--invalidlength
1075510893:trun(1752976169)<--invalidlength
1099156795:alac(1742569925)<--invalidlength
1106652272:jpeg(3439319704)<--invalidlength
1107417964:mfhd(1538756873)<--invalidlength
1128739407:trex(610792063)<--invalidlength
1173617373:vmhd(2809227644)<--invalidlength
1199327317:samr(257070757)<--invalidlength
1223984126:minf(1453635650)<--invalidlength
1225730123:subs(21191883)<--invalidlength
1226071922:gmhd(392925472)<--invalidlength
1274024443:m4ds(1389488607)<--invalidlength
1284829383:iviv(35224648)<--invalidlength
1299729513:stsc(448525299)<--invalidlength
1306664001:xml(1397514514)<--invalidlength
1316470096:dawp(1464185233)<--invalidlength
1323023782:mean(543894974)<--invalidlength
1379006466:elst(1716974254)<--invalidlength
1398928786:enct(4166663847)<--invalidlength
1423511184:srpp(4082730887)<--invalidlength
1447460576:vmhd(2307493423)<--invalidlength
1468795885:priv(1481525149)<--invalidlength
1490194207:sdp(3459093511)<--invalidlength
1539254593:hdlr(2010257153)<--invalidlength

• A Common Problem: Through extensive research, I've discovered that this is a widespread issue. Many people have experienced similar problems with cameras unexpectedly dying during recording, resulting in corrupted video files. While some have found success with tools like untrunc, recover_mp4.exe, or others that I've mentioned, these tools have not been helpful in my particular case!?!
• Similar Case on GPAC/MP4Box Forum: a relevant thread on the SourceForge GPAC/MP4Box forum where someone had a similar issue: https://sourceforge.net/p/gpac/discussion/287547/thread/20466c3e/.
• Tools that don't recognize the file include:
• Recover-mp4
• Shutter Encoder
• Handbrake
• VLC
• GPAC When I try to open the corrupted file in GPAC, it reports "Bitstream not compliant."
• My MP4Box GUI
• YAMB When I try to open the corrupted file in YAMB, it reports "IsoMedia File is truncated."
• Many other common video repair tools.

Additional Information and Files I Can Provide:

Is there any possibility of recovering more than just the first portion of this particular 21.4 GB video? While a significant amount of data appears to be missing, could those fragmented "moov" occurrences be used to somehow reconstruct a partial moov atom, at least enough to make more of the mdat data (even if incomplete) accessible?

Any insights into advanced MP4 repair techniques, particularly regarding moov reconstruction?

Recommendations for tools (beyond the usual video repair software) that might be helpful in analyzing the MP4 structure at a low level?

Anyone with experience in hex editing or data recovery who might be able to offer guidance?

Additional Information and Files I Can Provide:

Corrupt file metadata from Mediainfo:

<?xml version="1.0" encoding="UTF-8"?>
<MediaInfo xmlns="<https://mediaarea.net/mediainfo>" xmlns:xsi="<http://www.w3.org/2001/XMLSchema-instance>" xsi:schemaLocation="<https://mediaarea.net/mediainfo> <https://mediaarea.net/mediainfo/mediainfo_2_0.xsd>" version="2.0">
<creatingLibrary version="24.11.1" url="<https://mediaarea.net/MediaInfo>">MediaInfoLib</creatingLibrary>
<media ref="Z:\\Penjere\\01Season\\Production\\Ep11\\Dr.AzizTheGuestCam\\Corrupted.MP4">
<track type="General">
<FileExtension>MP4</FileExtension>
<Format>XAVC</Format>
<CodecID>XAVC</CodecID>
<CodecID_Compatible>XAVC/mp42/iso2</CodecID_Compatible>
<FileSize>23056715861</FileSize>
<StreamSize>23056715861</StreamSize>
<HeaderSize>176</HeaderSize>
<DataSize>23056088912</DataSize>
<FooterSize>626773</FooterSize>
<IsStreamable>No</IsStreamable>
<File_Created_Date>2025-01-23 06:05:54.544 UTC</File_Created_Date>
<File_Created_Date_Local>2025-01-23 09:05:54.544</File_Created_Date_Local>
<File_Modified_Date>2024-11-15 09:12:59.754 UTC</File_Modified_Date>
<File_Modified_Date_Local>2024-11-15 12:12:59.754</File_Modified_Date_Local>
</track>
</media>
</MediaInfo>

Metadata from camera itself (auto generated xml file):

<NonRealTimeMeta xmlns="urn:schemas-professionalDisc:nonRealTimeMeta:ver.2.00" xmlns:lib="urn:schemas-professionalDisc:lib:ver.2.00" xmlns:xsi="<http://www.w3.org/2001/XMLSchema-instance>" lastUpdate="2024-03-02T12:33:48+05:00">
<TargetMaterial umidRef="060A2B340101010501010D4313000000E8160286710306D2747A90FFFE064421"/>
<Duration value="57810"/>
<LtcChangeTable tcFps="30" halfStep="false">
<LtcChange frameCount="0" value="63263704" status="increment"/>
<LtcChange frameCount="57809" value="60350905" status="end"/>

</LtcChangeTable>
<CreationDate value="2024-03-02T12:33:48+05:00"/>
<VideoFormat>
<VideoRecPort port="DIRECT"/>
<VideoFrame videoCodec="AVC_3840_2160_HP@L51" captureFps="29.97p" formatFps="29.97p"/>
<VideoLayout pixel="3840" numOfVerticalLine="2160" aspectRatio="16:9"/>

</VideoFormat>
<AudioFormat numOfChannel="2">
<AudioRecPort port="DIRECT" audioCodec="LPCM16" trackDst="CH1"/>
<AudioRecPort port="DIRECT" audioCodec="LPCM16" trackDst="CH2"/>

</AudioFormat>
<Device manufacturer="Sony" modelName="ILCE-7RM4" serialNo="4294967295"/>
<RecordingMode type="normal" cacheRec="false"/>
<AcquisitionRecord>
<Group name="CameraUnitMetadataSet">
<Item name="CaptureGammaEquation" value="rec2100-hlg"/>
<Item name="CaptureColorPrimaries" value="rec709"/>
<Item name="CodingEquations" value="rec709"/>

</Group>

</AcquisitionRecord>

</NonRealTimeMeta>

https://i.redd.it/h3vrh6zb1ree1.png

https://preview.redd.it/eight-moov-ghosts-in-a-21-4-gb-mp4-v0-fkux2so58ree1.png?width=2559&format=png&auto=webp&s=c65620ef110ba8a2ec06445fb9c4875c3896513e

I know this is a complex issue, and I really appreciate anyone who takes the time to consider my problem and offer any guidance. Thank you in advance for your effort and for sharing your expertise. I'm grateful for any help this community can provide.

Hi everyone, I am preparing for my college placements and I'm currently deciding whether to follow the Striver DSA sheet or focus on LeetCode's Interview 150 problems. Which one would you recommend for efficient preparation and better coverage of commonly asked questions?

How to learn and master DSA? I am finding it incredibly hard? Is there any particular approach which will make it easier to learn and understand and crack interviews? How to get consistent? Please Dm

I am 20M
Currently i am learning DSA from a youtube channel
I want some certificates to put on my linkedIn
Can someone please tell me some free platforms where i can get a certificate of completion or anything like that for DSA.
I don't want to watch their specific course as i am doing it already from a youtube channel

I am 20M
Currently i am learning DSA from a youtube channel
I want some certificates to put on my linkedIn
Can someone please tell me some free platforms where i can get a certificate of completion or anything like that for DSA.
I don't want to watch their specific course as i am doing it already from a youtube channel

Hey ,

I’m entering my 3rd semester, and I’ve got Data Structures and Algorithms (DSA) and Object-Oriented Programming (OOP) in my coursework this time. Honestly, my programming fundamentals (Java) weren’t that strong last semester because I didn’t put in enough effort. But now, I want to make a solid comeback and aim to be the best in my class.

I want to develop a strong grip on DSA and OOP concepts, and I’m determined to work hard. I’d really appreciate your guidance on the following:

1. How to Master DSA and OOP:

   • What resources (books, online courses, or videos) should I follow?
   • Should I prioritize theoretical understanding or dive straight into coding?

2. Daily Routine/Roadmap:

   • How should I structure my day to consistently improve in these subjects?
   • How can I balance theory, practice, and revision effectively?

3. Best Practices for Coding:

   • How do I improve my problem-solving skills?
   • Are there any tips for debugging efficiently?

4. Motivation and Mindset:

   • Any advice on staying consistent and motivated during tough phases?

I’ve heard that DSA is the backbone of competitive programming and interviews, and I don’t want to miss out on mastering it. The same goes for OOP—understanding concepts like inheritance, polymorphism, and abstraction is crucial for writing clean and efficient code.

To anyone willing to share tips, resources, or even personal experiences, my DMs are open. I’m eager to learn from professionals and enthusiasts here because I know I won’t get this level of insight from anywhere else.

Let me know how you tackled these subjects or how I can make the most of my time. I’m ready to put in the work—I just need some direction!

Thanks in advance!

I have a common question. What is the difference between k-ary and n-ary trees in Data Structures and Algorithms? Are they both the same, or is the k-ary tree always fixed (e.g., k = 10) while n is more dynamic? I asked AI, but sometimes it gives me one answer and sometimes another.

I have tried a couple books but don't know where to begin. I try yt videos, I understand concepts but trying even medium leetcode problems puts me to shame. I can only think of brute force methods and sometimes not even that. Every time I try solving them, I feel like a failure. I am already in my second year of college (half way done) and I am scared about placements. If I can't solve basic sums how can I even begin specializing??
Sorry for venting out here.

TLDR; where do I learn dsa from and how do I get better at problem solving?

Original post: Summary: Summary: Animation video on Floyd-Warshall Algo

Read the full blog post here: https://www.interviewhelp.io/blog/posts/summary_summary_animation_video_on_floyd-warshall_/

Original post: Hash Tables Visually Explained

Read the full blog post here: https://www.interviewhelp.io/blog/posts/hash_tables_visually_explained/

Original post: How much DSA is enough to get a job at a Product based Company as Software Engineer?

Read the full blog post here: https://www.interviewhelp.io/blog/posts/how_much_dsa_is_enough_to_get_a_job_at_a_product_b/

Original post: Upload a full 4 hours animated course on DSA

Read the full blog post here: https://www.interviewhelp.io/blog/posts/upload_a_full_4_hours_animated_course_on_dsa/

Original post: Data structure

Read the full blog post here: https://www.interviewhelp.io/blog/posts/data_structure_/

Original post: Data Structures and Algorithms

Read the full blog post here: https://www.interviewhelp.io/blog/posts/data_structures_and_algorithms/

Original post: Need guidance on where to start DSA

Read the full blog post here: https://www.interviewhelp.io/blog/posts/_need_guidance_on_where_to_start_dsa/

Can anyone solve this question? https://www.hackerearth.com/problem/algorithm/the-pizza-eating-contest-397ec3cd-7df06718/

Hi All, I just started my DSA and wanted to target MAANG. I have a total of 7 years of work exp and it's totally into prod support roles where was no hands on coding. Right now, I want to concentrate more on DSA and will be preparing for System Design in parallel to this. Can someone please guide me how to start. I am an ECE graduate and can code in Python but can't provide optimal solutions. Please experts from this team, please advice...

pls help me find some final exams to solve

I want to make my dsa logic better can you suggest me some ways how can I achieve that

Hi, I want to upgrade my DSA skills so that I could increase my chances of getting a job at a Product Based Company as a Software Engineer, However I am unable to find a definite answer/ resource to this,

• I have seen many YouTube videos suggesting different concepts and strategies
• I have also seen some paid courses which even offer referrals

I felt these as very confusing, time consuming and sometimes not Trust worthy at all considering some sell these courses for monetary benefit.

Can anyone reading my question draft a solid plan based on real experience which has 90% chance of success irrespective of the company I apply for the role of Software Engineer. My Programming Language of preference is Python.

Original post: Summary: Animation video on Floyd-Warshall Algo

Read the full blog post here: https://www.interviewhelp.io/blog/posts/summary_animation_video_on_floyd-warshall_algo/