Today I have done leetcode's February LeetCoding Challenge with cpp.

February LeetCoding Challenge 17

Description

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 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
• $2 \le n \le 3 * 10^4$
• $0 \le height[i] \le 3 * 10^4$

Solution

ah ha! done by myself without hint

class Solution {
public:
    int maxArea(vector<int>& height) {
        int len = height.size();
        int left = 0, right = len - 1;
        int answer = (right - left) * min(height[left], height[right]);
        while(left < right) {
            if(height[left] < height[right]) {
                int tmp = height[left];
                while(left < right && height[left] <= tmp) ++left;
                answer = max(answer, (right - left) * min(height[left], height[right]));
            } else {
                int tmp = height[right];
                while(left < right && height[right] <= tmp) --right;
                answer = max(answer, (right - left) * min(height[left], height[right]));
            }
        }
        return answer;
    }
};

// find the max (j - i) * (min(a_j, a_i))