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Container With Most Water Test | Pre-employment assessment - Testlify
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Container With Most Water Test

Overview of Container With Most Water Test

The goal is to find two lines, which together with x-axis forms a container, such that the container contains the most water

Skills measured

  • Two pointers
  • greedy

Available in



Coding Test


20 Mins





Use of Container With Most Water test

The solution approach calculates the maximum area of water that can be contained between vertical lines given their heights represented by an input vector.
The maxArea function takes a vector of integers height as input and returns an integer representing the maximum area.
The function initializes variables left and right to 0 and height.size() - 1, respectively. These variables represent the left and right pointers that traverse the height vector.
The variable ret is initialized to 0 and will store the maximum area found so far.
The solution uses a while loop with the condition left < right, which means the left pointer is not crossing or equal to the right pointer.
Inside the while loop, the solution calculates the area between the vertical lines represented by the left and right pointers. The area is calculated as the minimum of the heights at height[left] and height[right] multiplied by the distance between the two pointers, which is (right - left). The area formula is min(height[left], height[right]) * (right - left).

The max function is used to update the ret variable with the maximum value between the current ret and the calculated area. This ensures that ret always holds the maximum area found so far.

The solution then checks if the height at the left pointer, height[left], is less than the height at the right pointer, height[right]. If it is, it means the left pointer is pointing to a shorter vertical line compared to the right pointer. In this case, the left pointer is incremented by 1 (left += 1), moving it to the next position.

If the height at the left pointer is greater than or equal to the height at the right pointer, it means the right pointer is pointing to a shorter or equal-height vertical line compared to the left pointer. In this case, the right pointer is decremented by 1 (right -= 1), moving it to the previous position.

The loop continues until the left pointer crosses or becomes equal to the right pointer.

Finally, the function returns the maximum area ret that was calculated.

The intuition behind this solution is to use a two-pointer approach to iterate from both ends of the height vector towards the center. The idea is to maximize the area by choosing the vertical lines with the maximum possible height difference and the maximum distance between them. By continuously moving the pointers towards each other while updating the maximum area, the solution finds the maximum possible area.

Relevant for

  • Software Developer Engineer
  • Software Developer
  • Software Engineers

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Two pointers

The Two Pointers technique in the Container With Most Water problem involves using two pointers, one starting from the beginning and the other from the end of the array. By moving the pointers towards each other and calculating the area between them at each step, we can determine the maximum area that can be formed by the two lines. This technique is important because it allows us to efficiently search for the maximum area without having to consider all possible combinations, resulting in a faster and more optimized solution to the problem.



In the problem of Container With Most Water, the greedy skill covered is to constantly update the maximum area of water that can be held by moving the two pointers towards each other based on the height of the containers. This skill is important because it allows us to efficiently find the maximum possible area without having to consider all possible container combinations. By greedily selecting the next container to move inwards based on its height, we can quickly converge on the optimal solution and avoid unnecessary computations. This approach saves time and space complexity, making the solution more efficient.

The Container With Most Water test is created by a subject-matter expert

Testlify’s skill tests are designed by experienced SMEs (subject matter experts). We evaluate these experts based on specific metrics such as expertise, capability, and their market reputation. Prior to being published, each skill test is peer-reviewed by other experts and then calibrated based on insights derived from a significant number of test-takers who are well-versed in that skill area. Our inherent feedback systems and built-in algorithms enable our SMEs to refine our tests continually.

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