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 the line i is at (i, ai) and (i, 0). Find two lines, which, together with the x-axis forms a container, such that the container contains the most water.

Notice that you may not slant the container.

Example 1:

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

Input: height = [1,1]
Output: 1
Example 3:

Input: height = [4,3,2,1,4]
Output: 16
Example 4:

Input: height = [1,2,1]
Output: 2

Constraints:

n == height.length
2 <= n <= 3 104
0 <= height[i] <= 3 104

解答：贪心

时间复杂度O(n)，空间复杂度O(1)

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