leetcode 11. Container With Most Water (two pointer)

Posted by 111qqz on Thursday, April 13, 2017

TOC

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.

题意:n条竖直的线段 (i,0)->(i,a[i]),从中选2条,和x轴共同组成一个开口的容器,问容器的最大面积。

思路:一开始想错了,以为是最大连续矩形面积…还在想leetcode竟然考单调栈???

然而实际上只取两个线段,中间的线段有没有,长度,都是无所谓的。

因此two pointer就好了。。。

/* ***********************************************
Author :111qqz
Created Time :2017年04月13日 星期四 18时06分42秒
File Name :11.cpp
 ************************************************ */
class Solution {

    public:

    int maxArea(vector<int>& height) {
        int res = 0 ;
        int n = height.size();
        int head = 0 ;
        int tail = n-1;
        while (head<tail)
        {
        int h = min(height[head],height[tail]);
        res = max(res,(tail-head)*h);
        while (head<tail&&height[head]<=h) head++;
        while (head<tail&&height[tail]<=h) tail--;
        }
        return res;


    }

};

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