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 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.

Analyse: Set two variables, left and right to represent the leftmost and rightmost element respectively. We increase left and decrease right gradually. If the moving items are smaller than height[left] and height[right], then we don't need to change the value of left and right. Otherwise, we change the values and compare the area with the former computed one. 

Runtime: 32ms.

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