leetcode 11. Container With Most Water

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

思路：

使用索引技术来解决这个问题：左右双索引技术；并且实时更新 索引；

code：

class Solution {
public:
    int maxArea(vector<int>& height) 
    {
        int n=height.size();
        assert(n>=2);
        int left=0;
        int right=n-1;
        int res=0;
        //int i=1;用来调试的时候看输出的；
        while(left<=right)//如何更新 是一个难点；
        {
            int temp=(right-left)*min(height[left],height[right]);//宽*高；
            res=max(res,temp);
            //cout<<"第"<<i<<"次的容积是从："<<left+1<<"--"<<right+1<<":"<<res<<endl;
            if(height[left]<=height[right])
                left++;
            else 
                right--;
            //i++;
            // left++;
            // right--;
        }
        return res;
    }
};