Leetcode - Probklems

Mothers Day and Fathers Day Challenge problems

All codes for the Fathers Day and Mothers Day Challenge

🚀 LeetCode 119 - Pascal's Triangle II

Problem Description Given an integer rowIndex, return the rowIndex-th (0-indexed) row of Pascal's Triangle. In Pascal’s Triangle, each number is the sum of the two numbers directly above it.

Example:

Input: rowIndex = 3 Output: [1, 3, 3, 1]

Approach

We start with the first element 1 and iteratively build each row using the previous values. We update the list in reverse order to avoid overwriting values.

Key Takeaways

Pascal's Triangle builds from previous rows. Reverse traversal helps avoid overwriting values while updating.

🚀Leetcode 678 - Valid Parenthesis String

Problem Statement Given a string s containing only three types of characters: '(', ')', and '*', return true if s is valid.

A valid string must follow these rules:

Every '(' must have a corresponding ')'. Every ')' must have a corresponding '('. '(' must appear before the corresponding ')'. '*' can be treated as '(', ')', or an empty string "".

Examples

Input: s = "()" Output: true

Approach

We use a Greedy strategy to keep track of the range of possible open parentheses at any point:

Steps: Iterate through each character in the string. Update minOpen and maxOpen based on character: '(': increment both ')': decrement both '*': decrement minOpen, increment maxOpen If at any point maxOpen < 0, return false. If minOpen drops below 0, reset it to 0. After the loop, return true if minOpen == 0.