lintcode-medium-Container with Most Water

Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). nvertical 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.

Given [1,3,2], the max area of the container is 2.

 

思路：

用左右两个指针向中间移动，记录任一时刻的截面积，如果比之前的结果大，就更新结果

当左边高度大于右边事，如果移动左边，则接下来的结果不会大于现在的结果，所以要移动右边，反之亦然，结论是总是移动高度较小的边

public class Solution {
    /**
     * @param heights: an array of integers
     * @return: an integer
     */
    public int maxArea(int[] heights) {
        // write your code here
        
        if(heights == null || heights.length == 0)
            return 0;
        
        int left = 0;
        int right = heights.length - 1;
        int result = 0;
        
        while(left < right){
            int area = (right - left) * Math.min(heights[left], heights[right]);
            if(area > result)
                result = area;
            
            if(heights[left] > heights[right])
                right--;
            else
                left++;
            
        }
        
        return result;
    }
}