The following codes work by pypy 3

na=len(a)
nb=len(b)
dp=[[0]*(nb+1) for _ in range(na+1)]
for i in range(na):
    for j in range(nb):
        if a[i]==b[j]:
            dp[i+1][j+1]=dp[i][j]+1
        else:
            dp[i+1][j+1]=max(dp[i+1][j],dp[i][j+1])

suff=[[0]*(nb+1) for _ in range(na+1)]
for i in range(na-1,-1,-1):
    for j in range(nb-1,-1,-1):
        if a[i]==b[j]:
            suff[i][j]=suff[i+1][j+1]+1
        else:
            suff[i][j]=max(suff[i+1][j],suff[i][j+1])

cur = dp[na][nb]      
ret = 0
for i in range(na+1):
    used=[False]*(256)

    for j in range(nb):
        if used[ord(b[j])]==True:
            continue
        now=dp[i][j]+ suff[i][j+1] + 1
        if now == cur+1:
            used[ord(b[j])]=True
            ret+=1
return ret

Here is LCS Returns problem solution - https://programs.programmingoneonone.com/2021/07/hackerrank-LCS-return-problem-solution.html

Can anyone help me in this?

M=62
def func(c):
    if(c>='a' and c<='z'):
        return ord(c)-97
    if(c>='A' and c<='Z'):
        return ord(c)-65
    return ord(c)-48

def tutzkiAndLcs(a, b):
    n=len(a)
    m=len(b)
    dp=[]
    dpr=[]
    position=[[] for i in range(M)]
    for i in range(1,m+1,1):
        position[func(b[i-1])].append(i)
    for i in range(n+2):
        dp+=[[0]*(m+2)]
        dpr+=[[0]*(m+2)]
    
    for i in range(1,n+1):
        for j in range(1,m+1):
            if a[i-1]==b[j-1]:
                dp[i][j]=dp[i-1][j-1]+1
            else:
                dp[i][j]=max(dp[i-1][j],dp[i][j-1])

            
    for i in range(n,0,-1):
        for j in range(m,0,-1):
            if(a[i-1]==b[j-1]):
                dpr[i][j]=1+dpr[i+1][j+1]
            else:
                dpr[i][j]=max(dpr[i+1][j],dpr[i][j+1])
                
    #print(position)
    #print(dp)
    #print(dpr)   
    
    ans = 0
    for i in range(0,n+1,1):
        for c in range(0,26,1):
            for j in range(0,len(position[c]),1):
                p=position[c][j]
                if(dp[i][p-1] + dpr[i+1][p+1] == dp[n][m]):
                    ans+=1
                    break
    print(ans)    
    return ans

https://codeforces.com/blog/entry/103769#comment-921563

explanation and code

I had a tough time understanding the problem when I tried it back then, so I figured I'll make things simple and have just posted a simple and different way of explanation on the youtube. Feedbacks much much appreciated, thank you. Link is https://youtu.be/abFiUC-UF0c Its just HackerRank has been my home site for learning, & I am just looking for a feedback on if I was able to explain the problem well and thoroughly, thank you :)