LeetCode #11: Container With Most Water

The Problem

Given an integer array height of length n, find two lines that form a container with the x-axis that can hold the most water.

The container's area is: width × min(height[i], height[j]).

Examples

🧠 Key Insight: Why Two Pointers?

The brute force O(n²) solution checks every pair — but we can do better.

This reduces time from O(n²) → O(n).

✅ Solution (JavaScript)

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

  while (left < right) {
    const width = right - left;
    const currentHeight = Math.min(height[left], height[right]);
    const area = width * currentHeight;
    
    maxArea = Math.max(maxArea, area);

    // Move the shorter pointer
    if (height[left] < height[right]) {
      left++;
    } else {
      right--;
    }
  }

  return maxArea;
}

🎮 Try It: Water Container Visualizer

Watch how the two pointers move and the area changes in real time.