Two Pointer

O(n)

class Solution {
    public int maxArea(int[] height) {
        if (height == null || height.length == 0) return 0;

        int left = 0, right = height.length - 1;
        int max = 0;
        while (left < right){
            int h = Math.min(height[left], height[right]);
            max = Math.max(max, h * (right - left) );
            while (left < right && height[left] <= h) left++;
            while (left < right && height[right] <= h) right--;
        }

        return max;
    }
}