Problem Description
You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]).
Find two lines that together with the x-axis form a container, such that the container contains the most water.
Return the maximum amount of water a container can store.
Notice that you may not slant the container.
Examples
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
Python Solution
class Solution:
def maxArea(self, height: List[int]) -> int:
left, right = 0, len(height) - 1
max_area = 0
while left < right:
width = right - left
h = min(height[left], height[right])
area = width * h
max_area = max(max_area, area)
if height[left] < height[right]:
left += 1
else:
right -= 1
return max_area
Java Solution
class Solution {
public int maxArea(int[] height) {
int left = 0;
int right = height.length - 1;
int maxArea = 0;
while (left < right) {
int width = right - left;
int h = Math.min(height[left], height[right]);
int area = width * h;
maxArea = Math.max(maxArea, area);
if (height[left] < height[right]) {
left++;
} else {
right--;
}
}
return maxArea;
}
}
C++ Solution
class Solution {
public:
int maxArea(vector& height) {
int left = 0;
int right = height.size() - 1;
int maxArea = 0;
while (left < right) {
int width = right - left;
int h = min(height[left], height[right]);
int area = width * h;
maxArea = max(maxArea, area);
if (height[left] < height[right]) {
left++;
} else {
right--;
}
}
return maxArea;
}
};
JavaScript Solution
/**
* @param {number[]} height
* @return {number}
*/
var maxArea = function(height) {
let left = 0;
let right = height.length - 1;
let maxArea = 0;
while (left < right) {
const width = right - left;
const h = Math.min(height[left], height[right]);
const area = width * h;
maxArea = Math.max(maxArea, area);
if (height[left] < height[right]) {
left++;
} else {
right--;
}
}
return maxArea;
};
C# Solution
public class Solution {
public int MaxArea(int[] height) {
int left = 0;
int right = height.Length - 1;
int maxArea = 0;
while (left < right) {
int width = right - left;
int h = Math.Min(height[left], height[right]);
int area = width * h;
maxArea = Math.Max(maxArea, area);
if (height[left] < height[right]) {
left++;
} else {
right--;
}
}
return maxArea;
}
}
Complexity Analysis
- Time Complexity: O(n) where n is the length of the input array
- Space Complexity: O(1) as we only use a constant amount of extra space
Solution Explanation
This solution uses the two-pointer technique:
- We start with two pointers at the ends of the array
- For each pair of lines:
- Calculate the width (distance between lines)
- Calculate the height (minimum of the two line heights)
- Calculate the area and update maximum if needed
- Move the pointer at the shorter line inward
Key points:
- Moving the shorter line inward can only increase the area
- Moving the taller line inward can only decrease the area
- We only need to traverse the array once
- We handle edge cases (empty array, single element) properly