LeetCode 11. Container With Most Water

Two Pointer

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 * 10^4

• 0 <= height[i] <= 3 * 10^4

Solution:

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