Hello, Codeforces!

I am pleased to invite you to participate in ICPC Beginner Contest for Newbies-Round 5, which will be held at Thursday, July 25, 2024 at 12:30 UTC+5.5. You will be given 19 problems and 12 hours to solve them. Problems are sorted in difficulty order.

Plz Join this link.

UPD: The contest registration has been started.

UPD2: Congrats for the winners:

1)Banis [Perfect 19/19]

2)whitepalace [Perfect 19/19]

3)Console Crashers:_GoDGaMerS_,Kenil_Patel_183,tirthgohil1410

4)Luchador

5)d1312

First Solves:

A)whitepalace

B)gauravandbhagat

C)Luchador

D)Luchador

E)whitepalace

F)Luchador

G)whitepalace

H)whitepalace

I)whitepalace

J)Banis

K)whitepalace

L));:DeadMan69,geekyvishal,Rajdeep10

M)Banis

N)Banis

O)Luchador

P)Banis

Q)Banis

R)Banis

S)whitepalace

Hello, Codeforces!

I am pleased to invite you to participate in ICPC Beginner Contest for Newbies-Round 4, which will be held at Wednesday, July 24, 2024 at 10:05 UTC+5.5. You will be given 19 problems and 8 hours to solve them. Problems are sorted in difficulty order.

Plz Join this link.

UPD: The contest has been extended by 1 hour.

UPD2: Congrats for the winners:

1) Banis

2) YhuanDebeste

3) supremeashu

4) LakhimpurKheri

5) Once_ILoveSabnaj

Hello, Codeforces!

I am pleased to invite you to participate in ICPC Beginner Contest for Newbies-Round 3, which will be held at Sunday, July 21, 2024 at 17:40 UTC+5.5. You will be given 19 problems and 48 hours to solve them. Problems are sorted in difficulty order.

Plz Join this link.

Congrats for the winners:

1) Skill Issue: wiseeldrich2004,vibhu_k2003,sojabhai

2) anango

3) Rohak

4) ;): Rajdeep10,DeadMan69,geekyvishal

5) whitepalace

Hello, Codeforces!

I am pleased to invite you to participate in ICPC Beginner Contest for Newbies- Round 2, which will be held at Friday, July 19, 2024 at 15:05 UTC+5.5. You will be given 19 problems and 48 hours to solve them. The difficulty of contest is 1 star. Problems are sorted in difficulty order.

Plz Join this link.

Congrats for the winners:

1) spampots

2) kushagramaster2004

3) anango

4) butterpaneer

5) abo7ady

6) dualthread

7) hemckerOO7

Problem Statement Takahashi tried to type a string S consisting of lowercase English letters using a keyboard.

He was typing while looking only at the keyboard, not the screen.

Whenever he mistakenly typed a different lowercase English letter, he immediately pressed the backspace key. However, the backspace key was broken, so the mistakenly typed letter was not deleted, and the actual string typed was T.

He did not mistakenly press any keys other than those for lowercase English letters.

The characters in T that were not mistakenly typed are called correctly typed characters.

Count the number of subsequences in String T can form String S.

Constraints: S and T are strings of lowercase English letters with lengths between 1 and 2×(10)^5, inclusive.

Input: The input is given from Standard Input in the following format: S T

Output: Print number of subsequences of string T can form String S.

Sample Input 1: abc axbxyc

Sample Output 1: 1

Explaination: abc can form subsequence in (1,3 and 6) positions.

Sample Input 2: abac abacusabacus

Sample Output 2: 7

Explaination: abac can form subsequence in (1,2,3,4), (1,2,3,10),(1,2,7,10),(1,2,9,10),(1,8,9,10),(3,8,9,10) and (7,8,9,10) positions.

Sample Input 3: aaaaa aa

Sample Output 3: 0

What's the approach for this problem?

Hey from 4th problem of codechef starters felt difficult and from c problem of atcoder beginner feels difficult. what are the resources to do?