Container With Most Water

Problem

Given n vertical lines with heights height[i], find two lines that together with the x-axis hold the most water. Return the maximum area.

Constraints

• 2 ≤ height.length ≤ 10⁵
• 0 ≤ height[i] ≤ 10⁴

Approach — Two Pointers

This is a Two Pointers problem. The idea: walk two indices through the data together (or toward each other), turning an O(n²) pair search into one linear pass. Work through the reference code below line by line, then re-derive it yourself in the editor — that's how the pattern sticks.

Complexity: O(n) time, O(1) extra space.

Solution code

Python

class Solution:
    def maxArea(self, height):
        l, r, best = 0, len(height) - 1, 0
        while l < r:
            best = max(best, (r - l) * min(height[l], height[r]))
            if height[l] < height[r]:
                l += 1
            else:
                r -= 1
        return best

Java

class Solution {
    public int maxArea(int[] height) {
        int left = 0;
        int right = height.length - 1;
        int maxArea = 0;
        while (left < right) {
            int h = Math.min(height[left], height[right]);
            maxArea = Math.max(maxArea, h * (right - left));
            if (height[left] < height[right]) {
                left++;
            } else {
                right--;
            }
        }
        return maxArea;
    }
}

Practice it

Reading a solution isn't the same as being able to write it under pressure. Open this problem in the in-browser editor, hide the solution, and solve it from scratch — your code runs against real test cases instantly.