containerWithMostWater.cpp

// 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

class Solution {
public:
    int maxArea(vector<int>& height) {
        int left = 0;
        int right = height.size()-1;
        int max_area = 0;
        int run_area, smaller_h;
        int length = height.size() - 1;
        while (left < right) {
            smaller_h = height[left] > height[right]? height[right]: height[left];
            run_area = smaller_h * length;
            max_area = max(max_area, run_area);
            if (smaller_h == height[left]) {
                left++;
            } else {
                right--;
            }
            length--;
        }
        return max_area;
    }
};