Lecture 135: Longest Common Subsequence || DP on Strings

In this Video, we are going to learn about Dynamic Programming. This Video marks the start of India's Biggest DP Series.
There is a lot to learn, Keep in mind “ Mnn bhot karega k chor yrr apne se nahi hoga ya maza nahi aara, Just ask 1 question “ Why I started ? “
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Notes Link: drive.google.c...
Slides Link: drive.google.c...
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Questions Links:
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[@anushkatyagi4249]

Appreciation for your efforts sir👍

[@Kinggaming-hp3qp]

really helpful bhaiya this series is very popular in future .

[@kunalbhika6424]

Understood😁😁

[@pramantomar822]

Loving the series ❤️❤️❤️❤️❤️❤️❤️❤️

[@harpratapsinhnakoom3540]

Feeling proud to reach near the end

[@FaizanKhan-gfaizank]

Couldn't have been better!!

[@pragyaverma2105]

Thank you ji ❤

[@bestlyrical3843]

Amazing content

[@manishdv1331]

Sir apka ye series maine kuch hi din pehle start kiya hai .
You are providing an amazing content which makes it easy for anyone to understand computer programming.
You are doing an amazing job!! Thank you sir!! @LoveBabbar

[@anshikasingh4158]

mazza aaya

[@NiteshYadav-dg8lh]

🔥🔥

[@itspurelypassionate]

Thanks!

[@VinodKumar-hm6do]

Best sir happie to be student of you

[@GauravHaritas]

Bhaiya #QnA Why didn't you go to foreign country for job purpose or to stay there itself ?

[@BombSquadHindiTipsTricks]

can this ques be solved using 4 variables only?

[@vedantraut256]

// COMPLETE CODE WITH COMMENTS
class Solution {
public:
int solve(string& a, string& b, int i, int j){
// Base Case
if(i == a.length())
return 0;
if(j == b.length())
return 0;
int ans = 0;
if(a[i] == b[j])
ans = 1 + solve(a, b, i+1, j+1);
else
{
ans = max(solve(a, b, i+1, j), solve(a, b, i, j+1));
}
return ans;
}
int solveMem(string& a, string& b, int i, int j, vector &dp){
// Base Case
if(i == a.length())
return 0;
if(j == b.length())
return 0;
if(dp[i][j] != -1)
return dp[i][j];
int ans = 0;
if(a[i] == b[j])
ans = 1 + solveMem(a, b, i+1, j+1, dp);
else
{
ans = max(solveMem(a, b, i+1, j, dp), solveMem(a, b, i, j+1, dp));
}
return dp[i][j] = ans;
}
int solveTab(string& a, string& b){
int n1 = a.length();
int n2 = b.length();
vector dp(n1+1, vector (n2+1, 0));
for(int i = n1-1; i>=0; i--){
for(int j = n2-1; j>=0; j--){
int ans = 0;
if(a[i] == b[j])
ans = 1 + dp[i+1][j+1];
else
{
ans = max(dp[i+1][j], dp[i][j+1]);
}
dp[i][j] = ans;
}
}

return dp[0][0];
}
int solveSpaceOP(string& a, string& b){
int n1 = a.length();
int n2 = b.length();
vector dp(n1+1, vector (n2+1, 0));
vector currRow(n2+1, 0);
vector nextRow(n2+1, 0);
for(int i = n1-1; i>=0; i--){
for(int j = n2-1; j>=0; j--){
int ans = 0;
if(a[i] == b[j])
ans = 1 + nextRow[j+1];
else
{
ans = max(nextRow[j], currRow[j+1]);
}
currRow[j] = ans;
}
nextRow = currRow;
}

return nextRow[0];
}
int longestCommonSubsequence(string text1, string text2) {
// RECURSION
// return solve(text1, text2, 0, 0);
// RECURSION + MEMOIZATION
/*
int n1 = text1.length();
int n2 = text2.length();

vector dp(n1+1, vector (n2+1, -1));
return solveMem(text1, text2, 0, 0, dp);
*/
// TABULATION
// return solveTab(text1, text2);
// SPACE OPTIMIZATION
return solveSpaceOP(text1, text2);
}
};

[@ultimategyani6412]

Bhai for loop ulte se hi kyu chalaye tabular wle mein...sidhe kyu ni chla skte???🥲

[@codingindisguise]

@@ultimategyani6412 Bhai loop seedha Top-Down mei lagate hain i.e. Memoization mei. Tabulation ka concept hi Bottom-Up approach hai toh ulta chalta hai...

[@sahilsingh5695]

we need more people like you

[@Anandkumar09876]

TLE aa raha hai

[@jaydhanwalkar9665]

UNDERSTOOD+++++++;

[@atifhu]

top down approach is no more accepted in my solution.

[@karthikmadan]

pass string by reference

[@akmarkan2490]

Why does it matter bro???​@@karthikmadan

[@deepakumar01]

Sir aapne top down me jo space Kam karne k liye do row liya hai usme aapne bola unki size min(lengths of strings) but ye galat hai aapko max Lena padega

[@nitishkumar-ol1fx]

❤❤

[@ajaychandel9976]

maza aa gaya🔥🔥🔥🔥🔥🔥

[@vishalgarna4580]

All clear bhaiya 😊😊😊

[@praveennemagoudar3442]

U r genius Bhaiya. Hats off. GOD of DSA.

[@arvindmali5179]

Amazing video as always....Thankkk youuuu bhaiya😍

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❤❤❤❤❤❤❤❤

[@keshavgupta333]

Bhaiya apki videos great hai

[@harshdubey4030]

understood ++

[@RandomGuy-xq1hk]

nice video ❤❤❤

[@ravindrashinde9305]

One and only one best series on DP👌

[@mitalisaraswat57]

[@dakshkumar7765]

😀

[@MittuRohith]

🤗

[@iteself_me]

58 ✅completed 👍Liked 04:12

[@vimalrai2092]

i noticed the mistake of +1 in vector intialization in the solveTabulation function earlier😁😁😁

[@Sambyal-n2y]

Appreciate your work. Thank you so much.

[@Motivational_talks]

yes understand ++

[@MrKB_SSJ2]

SOOO GENIUS ANSWER YOOOOOOOO

[@codingindisguise]

L views, W content❤

[@harshik7460]

how to print that lcs ??

[@jatinranjan7954]

Arigato gozaimasu🙇‍♂

[@nothinginsideme]

Very nice explanation sir, thank you so much

[@mycollegeLife.]

Nice nhi ....... phaaduuuuuuuu

[@studygainer5482]

completed

[@apurav363]

Thankyou bhaiya ❤

[@Deepak-um1zq]

Thank you bhaiya for such amazing content.☺

[@kumarshubham4327]

consistency++

[@arnavumarkar8259]

nice

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thanks love bober

[@parthagarwal1086]

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[@KratosProton]

t

[@KratosProton]

a

[@abhaythakur2597]

very well explained

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👍

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[@rahulsinghaswal07]

bhut asani se samjh aa gya bhaiya

[@huzaifaqureshi3329]

Thank you sir 🙌

[@Vital_Truth]

I really love to learn by you 😍❤

[@priyanshukhandelwal6631]

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🔥

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bhadiya

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samagh aa gaya

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[@sukhjitsingh959]

Thanks Babbar Sir Fire 🔥 back to finish Dp series

[@manishdv1331]

Sir apka guidance mujhe sahi mai zaroorat hai iss stream se related
Mai iss saal jee mains mein qualify hua hu aur apka reply bahut help karega sir
So where can I send a message to you sir??
I tried on Instagram, Gmail and LinkedIn.
(Ignore my grammar)

[@KratosProton]

e

[@sujalkumar4948]

sir ish series ke play list link ??

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Bhaiya ajhi khatam kardo DP Series maja a jaiga 😅

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Dil Jit Liya Bhaiyaa

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Reach++;