2D Arrays Practice | Matrix Transpose & Rotation, Pascal's Triangle | Lecture 21 | Java & DSA Course

The best way to ace programming is by solving problems. This lecture is a continuation of the previous lecture where we discussed in depth about Multi-dimensional arrays. In this lecture, we will solve some important questions related to 2-D Arrays. We will first understand the approach to solve the problem, then implement the algorithm in our code, and finally will have a quick dry run so there won't be any confusion in the algorithm or the code.

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Timestamps
00:00 = Intro
00:37 = Recap
03:38 = Today's checklist
04:02 = Problem 01 : Transpose of matrix
08:03 = Problem 01 : Transpose of matrix code
13:00 = Problem 01 : Transpose of matrix dry run
18:00 = Problem 02 : Transpose of matrix inplace
20:14 = Problem 02 : Transpose of matrix inplace - Testing swap code
22:30 = Problem 02 : Transpose of matrix inplace logic
30:51 = Problem 02 : Transpose of matrix inplace - final code
31:50 = Non-square matrix condition
32:45 = Problem 02 : Transpose of matrix inplace dry run
34:49 = Problem 03 : Rotate a matrix 90 degrees clockwise
38:50 = Problem 03 : Rotate a matrix 90 degrees clockwise code
45:34 = Problem 04 : Return n rows of Pascal's triangle
52:13 = Problem 04 : Return n rows of Pascal's triangle code
59:15 = Problem 04 : Return n rows of Pascal's triangle dry run
01:05:00 = Summary
01:07:26 = About next lecture

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[Raj]

noted point :- rotating an 2d array by 90 clockwise === first take transpose then reverse each row.

[piyushgupta]

I have learnt from many DSA teachers . Some of them are best in market but mam you are on the another level, easiest explaination ever. Thank You for you blessing. Thank You PW .

[itshurtyr]

lecture aisa banao ki 4 din kya 4 janmo tak ARRAY yaad rahe ❤❤❤❤❤❤😍😍😍😍

[omkarmatte]

thanks for good question practice and building our logic 👌

[BaapDeveloper]

You want to Learn DSA
Best place and free
Thank you all CW
Team ❤

[vaibhav]

For pascal question:
static int[][] pascal(int n){
int[][] pascal = new int[n][n];
for(int i=0;i<n;i++){
pascal[i][0] = 1;
for(int j=1;j<i+1;j++){
pascal[i][j] = pascal[i-1][j] + pascal[i-1][j-1];
}
}
return pascal;
}

[Deeptiharshkla]

solutution reverse rows-
static void reverse(int [][]arr, int r, int c ){
int temp;
for(int i=0;i<r;i++){
for(int p1=0, p2=c-1 ; p1<=p2 ; p1++, p2--)
{
temp= arr[i][p1];
arr[i][p1]=arr[i][p2];
arr[i][p2]=temp;
}
}
PrintArrays(arr);
}
Thank You So Much Mam, Aap Bahut Accha DSA Padhate Ho Ek Ek Qu Clear Ho jata Hain Mind Me

[sharadsharma]

for rotation of an array by 90 degree, simply use this loop instead of transpose and reverse.
for(int j=0;j<n;j++){
for(int i=m-1;i>=0;i--){
System.out.print(a[i][j]+" ");
}}

[VikasGupta-oklh]

one thing to add the method of caculating the inplace transpose is only effective when the number of rows and columns are same hence better to go with using extra space

[SahilAnsari-hr]

pascal ko kitna aasani se samjhaya thanku mam

[anshu_shree]

please upload assignment of 2d array and its solution

[kailashrabari]

mam notes wali website nahi open ho rahi hai

[educationtreebysarbjotsing]

i request to the the team of @College Wallah please provide this video download for 480P. i hope you will solve this problem as soon as possible.

[sagarchawla]

LINK TO NOTES ANS ASSIGNMETNS IS NOT WORKING !!!! LECTURE IS GREAT

[mhtsingh]

Placement ke liye aptitude ka bhi course start karaya jaye

[jeetukumar]

Mam one request pleasure aap jb bhi new question le to new file bnaye jyada code ek file me thoda kam smjh aata h
Vese you are a great teacher 🥰

[adityaghatiya]

Mam notes and assignment link is not opening.

[vanshgangwar]

I just want to know about this course, how this teacher is teaching I have java in my 4th sem so can i teach from here for better understanding

[shyamlalbhardwaj]

Jaisa aapne pda rakha hain na mam aisa koi pda nahi sakta thanks mam

[rvstech]

hi there am unable to find the assignements and the notes can anyone help