[leetcode 11]Container With Most Water

1 题目：

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.

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 Array Two Pointers

 

2 思路：

天资不才，只能想出O(n^2)的方法，好吧，这个闭着眼睛随意想想也能想出来。然后，一个特例就通不过了。

 

看了看别人的思路，有一种方法O(n)。

https://leetcode.com/discuss/11482/yet-another-way-to-see-what-happens-in-the-o-n-algorithm

详细说明见别人的解说，在草稿纸上结合着画画就出来了。

 

3 代码

n^2

    public int maxArea(int[] height) {
        int len = height.length;
        int maxArea = Math.min(height[len-1],height[0])*(len-1);
        for(int i = len-1; i >= 0 ; i--){
            for(int j = 0; j < i; j++){
                if(height[j] < height[0]) continue;
                int min = Math.min(height[i],height[j]);
                int temp = min * (i-j);
                if(temp > maxArea){
                    maxArea = temp;
                }
            }
        }
        return maxArea;
    }

n

    public int maxArea(int[] height) {
        int low = 0;
        int len = height.length;
        int high = len - 1;
        int maxArea = 0;
        while(low < high){
            int temp = Math.min(height[low],height[high])*(high-low);
            if(temp>maxArea){
                maxArea = temp;
            }
            if(height[low]<height[high]){
                low++;
            }else{
                high--;
            }
        }
        return maxArea;
    }