Classic example
Input
heights = [1, 8, 6, 2, 5, 4, 8, 3, 7]
Output
49
Choose lines at indices 1 (height 8) and 8 (height 7): area = min(8,7) * (8-1) = 7 * 7 = 49.
Full lesson preview
Find the maximum area formed by two lines
Given heights of vertical lines on the x-axis, find the maximum area formed between any two lines using the two-pointer technique.
Python practice15 minTwo Pointers & Sliding WindowIntermediateLast updated March 26, 2026
Problem statement
You are given a list of non-negative integers heights where each element represents the height of a vertical line at that index. A container is formed between two lines i and j (i < j) and the area it can contain is min(heights[i], heights[j]) * (j - i). Return the maximum area that can be formed by any two lines.
You should implement an algorithm with O(n) time complexity and O(1) additional space using the two-pointer approach.
Task
Implement an efficient two-pointer solution that computes the maximum water container area in O(n) time and O(1) extra space.
Examples
Input format
A single list of integers representing heights: heights
Output format
An integer representing the maximum possible area.
Constraints
2 <= len(heights) <= 10^5; 0 <= heights[i] <= 10^4. Expected time: O(n), extra space: O(1).
Samples
Sample 1
Input
[1, 1]
Output
1
Only two lines with height 1 and distance 1 => area = 1.