LeetCode刷题笔记--11. Container With Most Water

11. Container With Most Water

Medium

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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

这道题看上去挺有意思的。一开始我用暴力法来做，结果超时了。

暴力法的代码：

class Solution {
public:
    int maxArea(vector<int>& height) {
        int ans=0x80000000;
        for(int i=0;i<height.size();i++)
        {
            for(int j=i+1;j<height.size();j++)
            {
                ans=max(ans,min(height[j],height[i])*(j-i));
            }
        }
        
        return ans;
    }
};

看来需要找一些快速的方法来做。下面是看了别人的代码自己写的。有点不能确定这个算法，但是也找不出来反例证明这个算法不对。

class Solution {
public:
    int maxArea(vector<int>& height) {
        int i=0;
        int j=height.size()-1;
        int ans=0;
        while(j>i)
        {
            ans=max(ans,(j-i)*min(height[i],height[j]));
            if(height[i]<height[j])i++;
            else j--;
        }
        return ans;
    }
};