【LeetCode】11. Container With Most Water

11. Container With Most Water

Description：
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.
Difficulty：Medium

Example:

Input: [1,8,6,2,5,4,8,3,7]
Output: 49

方法1：双指针

• Time complexity : $O\left ( n \right )$O(n)
• Space complexity : $O\left ( 1 \right )$O(1)
  思路：
  左指针从0开始，右指针从n-1开始，计算完面积后，短边指针移动，直到找到比之前长的边为止，停止条件，左右指针相遇。

class Solution {
public:
	int maxArea(vector<int>& height) {
		int l = 0;
		int r = height.size() - 1;
		int max_area = 0;
		while (l < r) {
			int h = min(height[l], height[r]);
			max_area = max(max_area, h * (r - l));
			while (height[l] <= h && l < r) l++;
			while (height[r] <= h && l < r) r--;
		}
		return max_area;
	}
};