Tags: "leetcode", "java", "two-pointers", access_time 1-min read

Container With Most Water

Created: January 26, 2019 by [lek-tin]

Last updated: February 27, 2020

Given n non-negative integers a1, a2, …, an , where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the container contains the most water.

Note You may not slant the container and n is at least 2.

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:

Input: [1,8,6,2,5,4,8,3,7]
Output: 49

Solution:

class Solution {
    public int maxArea(int[] heights) {
        int maxVol = 0;

        if (heights.length < 2) {
            return maxVol;
        }

        int left = 0;
        int right = heights.length - 1;

        while (left < right) {
            int leftHeight = heights[left];
            int rightHeight = heights[right];
            int newVol = (right - left) * Math.min(rightHeight, leftHeight);
            maxVol = Math.max(maxVol, newVol);
            if (leftHeight < rightHeight) {
                left++;
            } else {
                right--;
            }
        }

        return maxVol;
    }
}