2026 April 25 Problems

[daryl...@gmail.com]

Feel free to work on any of the problems you want; we'll have people present their solutions at 11:30.

Please post your solutions to this thread so others can use this as a reference.

Medium and hard problems are carried over from last week.

3884. First Matching Character From Both Ends Easy 81.7%

3853. Merge Close Characters Medium 54.6%

3841. Palindromic Path Queries in a Tree Hard 35.5%

We will have a different Zoom meeting that Bhupathi is providing this week:

Here is the meeting url:

https://us05web.zoom.us/j/82553858456?pwd=fnK5Vb0CcfFpv0lnouILjeEs2z2Khc.1 

Full details:

Topic: Leet Code meeting
Time: Mar 28, 2026 10:00 AM Pacific Time (US and Canada)
        Every week on Sat, 110 occurrence(s)
Please download and import the following iCalendar (.ics) files to your calendar system.
Weekly: https://us05web.zoom.us/meeting/tZYocuqgqzMuH9IuHUphHIiZ_4T4IndJLToX/ics?icsToken=DJFc88pL6-me_TneLwAALAAAAA70ShjYgLH6RfEnqUm5LK03v2OgtbXujwlKXRMVgIVWCY9aONPJMCycMlkhyPZ3XSrMVVgXDSYlGF_r7DAwMDAwMQ&meetingMasterEventId=MGJmt5lJTd6mPygcS0hiAQ
Join Zoom Meeting
https://us05web.zoom.us/j/82553858456?pwd=fnK5Vb0CcfFpv0lnouILjeEs2z2Khc.1

Meeting ID: 825 5385 8456
Passcode: 182596

[Anuj Patnaik]

class Solution:

def firstMatchingIndex(self, s: str) -> int:

low = 0

high = len(s) - 1

while low <= high:

if s[low] == s[high]:

return low

else:

low = low + 1

high = high - 1

return -1

[Bhupathi Kakarlapudi]

class Solution:

def firstMatchingIndex(self, s: str) -> int:

strlen = len(s)

i = 0

while( i < strlen):

if s[i] == s[strlen-1-i]:

return i

i += 1

return -1

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[Shahaj Vijayan]

for 3884. First Matching Character From Both Ends  

Solution 

class Solution {

public int firstMatchingIndex(String s) {

int len = s.length();

for (int i=0 ; i<= len/ 2; i++) {

if (s.charAt(i) == s.charAt(len - i - 1)) {

return i;

}

}

return -1;

}

}

Thanks 

Shahaj Vijayan 

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Thanks

Shahaj Vijayan

[Jagrut]

3884. First Matching Character From Both Ends Easy 81.7%

class Solution:

def firstMatchingIndex(self, s: str) -> int:

n = len(s)

for i in range(0, n):

if s[i] == s[n - i - 1]:

return i

return -1

3853. Merge Close Characters Medium 54.6%

class Solution:

def mergeCharacters(self, s: str, k: int) -> str:

st = list(s)

keep_going = True

start = 0

while keep_going:

keep_going, start = self.merge(st, k, start)

return ''.join(st)

def merge(self, st: list, k: int, start: int) -> tuple[bool, int]:

for i in range(start, len(st)):

for j in range(i + 1, min(i + k + 1, len(st))):

if st[i] == st[j]:

st.pop(j)

return True, max(0, i - k)

return False, -1