11. Container With Most Water (opens new window)

Description

Difficulty: Medium

Related Topics: Array (opens new window), Two Pointers (opens new window), Greedy (opens new window)

You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the i^th 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.

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

Constraints:

• n == height.length
• 2 <= n <= 10⁵
• 0 <= height[i] <= 10⁴

Solution

Language: JavaScript

/**
 * @param {number[]} height
 * @return {number}
 * 1.暴力解法
 * 遍历左右边
 * 找出所有面积
 * 取最大
 * 
 * 2.双指针法
 * 关键字：左右两边
 * 模式识别：需要移动左右两头的问题可以考虑双指针
 * 难点：如何移动指针
 * 相同情况下两边距离越远越好
 * 区域受限于较短边
 */
var maxArea = function(height) {
    let [l, r, maxArea] = [0, height.length - 1, 0];
    
    while (l < r) {
        const [lh, rh] = [height[l], height[r]];
        maxArea = Math.max(maxArea, Math.min(lh, rh) * (r - l));
        
        lh < rh ? l++ : r--;
    }
    
    return maxArea;
};