0011. Container With Most Water

https://leetcode.com/problems/container-with-most-water

Description

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 the line i is at (i, ai) and (i, 0). Find two lines, which, together with the x-axis forms a container, such that the container contains the most water.

Notice that you may not slant the container.

Example 1:

**Input:** height = [1,8,6,2,5,4,8,3,7]
**Output:** 49
**Explanation:** 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 2:

**Input:** height = [1,1]
**Output:** 1

Example 3:

**Input:** height = [4,3,2,1,4]
**Output:** 16

Example 4:

**Input:** height = [1,2,1]
**Output:** 2

Constraints:

• n == height.length

• 2 <= n <= 105

• 0 <= height[i] <= 104

ac1: 2 pointer

start from left & right, move smaller one forward

https://leetcode.com/problems/container-with-most-water/discuss/6099/Yet-another-way-to-see-what-happens-in-the-O(n)-algorithm

class Solution {
    public int maxArea(int[] height) {
        // edge cases
        if (height.length < 2) return 0;

        int l = 0, r = height.length - 1, max = 0;
        while (l < r) {
            int vol = (r - l) * Math.min(height[l], height[r]);
            max = Math.max(max, vol); // if current volume > sum, update

            if (height[l] < height[r]) {
                l++;
            } else {
                r--;
            }
        }

        return max;
    }
}