Container With Most Water

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[] height) {
        int n = height.length;
        int leftMaxIndex = 0;
        int rightMaxIndex = n - 1;
        int left = 0;
        int right = n - 1;
        while (left < right) {
            if (area(height, left, right) > area(height, leftMaxIndex, rightMaxIndex)) {
                leftMaxIndex = left;
                rightMaxIndex = right;
            } else if (height[left] <= height[right]) {
                left ++;
            } else {
                right --;
            }
        }
        return area(height, leftMaxIndex, rightMaxIndex);
    }
    
    private int area(int[] height, int left, int right) {
        return Math.min(height[left], height[right]) * (right - left);
    }
}