Leetcode Questions Solutions Explained 6

Learn to solve the LeetCode monotonic array problem faced in Amazon and Microsoft interviews by testing if the array is monotone increasing or decreasing with a pass and two booleans.

Learn to locate a peak element by binary search in logarithmic time for LeetCode 162, returning the index of a local maximum where elements exceed their neighbors.

Learn how to flip a binary matrix horizontally and invert it, turning zeros into ones and ones into zeros, using a two-pointer approach to reverse rows.

Determine if a string is a palindrome by removing non alphanumeric characters, converting to lowercase, and using two pointers; consider the empty string valid, as in Leetcode 125.

Learn to solve the LeetCode 680 valid palindrome II problem using a two-pointer method, allowing one removal to form a palindrome, with left and right checks and substring validation.

Learn to sum left leaves in a binary tree using a preorder traversal and a recursive helper that adds only left leaf values, as used in tech company interview questions.

Master the house robber problem with a dynamic programming bottom-up approach that tracks the maximum loot without robbing adjacent houses and uses a total-so-far array.

Detect duplicates in an integer array using a hash set for linear-time checks, returning true when a duplicate appears and false otherwise—an interview-ready approach used by Google, Facebook, and Microsoft.

An explanation of solving Leetcode 219: contains duplicate II, using a hash map to track indices and detect duplicates within k, achieving linear time.

Master dynamic programming with climbing stairs problem, using a bottom-up approach and fibonacci-like pattern to count distinct ways for n steps, as seen in Google, Microsoft, and Facebook interview questions.