011. Container With Most Water

At a Glance

• Topic: Array
• Pattern: Analyze Pattern
• Difficulty: Medium
• LeetCode: 011

Problem Statement

You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]).

Find two lines that together with the x-axis form a container, such that the container contains the most water.

Return the maximum amount of water a container can store.

Notice that you may not slant the container.

Example 1:

Input: height = [1,8,6,2,5,4,8,3,7] Output: 49 Explanation: The above vertical lines are represented by array [1,8,6,2,5,4,8,3,7]. In this case, the max area of water (blue section) the container can contain is 49.

Example 2:

Input: height = [1,1] Output: 1

Constraints:

n == height.length
2 <= n <= 105
0 <= height[i] <= 104

Approach & Solution Steps

• Brute force all pairs is O(n^2). Sorting is invalid because index distance matters. The optimal two-pointer scan is O(n).

Optimal JS Solution

function maxArea(height) {
	let left = 0;
	let right = height.length - 1;
	let best = 0;

	while (left < right) {
		best = Math.max(best, (right - left) * Math.min(height[left], height[right]));
		if (height[left] <= height[right]) left++;
		else right--;
	}

	return best;
}

Edge Cases & Pitfalls

• Always consider empty or null inputs.
• Watch out for off-by-one index errors.