Givennnon-negative integersa1,a2, ...,an, where each represents a point at coordinate (i,ai).nvertical lines are drawn such that the two endpoints of lineiis 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 andnis at least 2.

分析：这题是水桶问题最简单的一道，找左右两点，形成的矩阵面积最大。

方法：双指针

class Solution {
    public int maxArea(int[] heights) {
        if(heights == null || heights.length < 2){
            return 0;
        }

        int left = 0;
        int right = heights.length -1;
        int max = 0;
        while(left < right){
            if(heights[left] < heights[right]){
                max = Math.max(max, heights[left]*(right-left));
                left++;
            } else{
                 max = Math.max(max, heights[right]*(right-left));
                right--;
            }
        }
       return max;
    }
}