LeetCode 11. Container With Most Water

原题链接在这里:https://leetcode.com/problems/container-with-most-water/

题目:

Given n non-negative integers a1a2, ..., an , where each represents a point at coordinate (iai). n vertical lines are drawn such that the two endpoints of line i is at (iai) 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

题解:

双指针夹比,更新最大面积,每次移动小的那个夹板,因为储水量是由短的夹板决定的,移动大的夹板不会使面积更大.

Time Complexity: O(n). Space: O(1).

AC Java:

 1 public class Solution {
 2     public int maxArea(int[] height) {
 3         if(height == null || height.length == 0){
 4             return 0;
 5         }
 6         int res = 0;
 7         int l = 0;
 8         int r = height.length-1;
 9         while(l<r){
10             //r-l是底长, 取左右两侧高度较小者为高
11             res = Math.max(res, (r-l) * Math.min(height[l], height[r]));
12             //移动短的边
13             if(height[l] < height[r]){
14                 l++;
15             }else{
16                 r--;
17             }
18         }
19         return res;
20     }
21 }

类似Trapping Rain Water.

posted @ 2015-09-26 01:47  Dylan_Java_NYC  阅读(266)  评论(0编辑  收藏  举报