Arrays (15) Two Sum Best Time to Buy and Sell Stock Maximum Subarray Contains Duplicate Product

Understand the problem statement: Find two indices such that their values sum up to a target value.

Choose a suitable data structure (e.g., hash map) for efficient look-up.

Iterate through the array while checking if the complement (target - current value) exists in the map.

Store each value and its corresponding index in the map for future reference.

Return the indices of the two numbers that add up to the target.

Read the problem statement: Determine the maximum profit from one buy and one sell.

Initialize variables to track the minimum price observed and the maximum profit.

Iterate through the price array

Update the minimum price if the current price is lower.

Calculate potential profit by subtracting the minimum price from the current price.

Update the maximum profit if the potential profit is higher.

Return the maximum profit found.

Review the problem: Find the contiguous subarray with the maximum sum.

Initialize variables for the maximum sum and the current sum (e.g., using Kadane’s algorithm).

Iterate through the array

Update the current sum by adding the current element.

If the current sum exceeds the maximum sum, update the maximum sum.

Reset the current sum to zero if it becomes negative.

Return the maximum sum found.

Understand the task: Check if there are any duplicates in the array.

Utilize a set to track seen elements.

Iterate through the array

If an element is already in the set, return true (indicating a duplicate).

If not, add the element to the set.

If the loop completes without finding duplicates, return false.

Read the problem: Calculate the product of all elements except the current one for each index.

Initialize two output arrays (left products and right products).

Fill the left products array by multiplying all previous elements.

Fill the right products array by multiplying all following elements.

Construct the result array by multiplying corresponding elements from left and right products.

Return the result array.

This checklist outlines the essential steps for each of the specified array problems.