Container With Most Water -- leetcode

原题

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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 and n is at least 2.

翻译

给你一串数字a1,a2,a3...,每一个数字表明坐标系上一个点,如a3 = 4的话就是表明(3,4)这个点.从这些全部的点中找出两个点,这两个点知足: 以这两个点往x轴作垂线,与x轴造成的水桶能够盛下作多的水,即面积最大.
如 (1, 2, 5) 面积为: 2; (3, 2, 4) 面积为 6

解题思路

• 定义一个头指针(lo)指向开始,再定义一个尾指针(hi)指向数组的末尾.

• 初始的面积是最外面两条边最小的乘他们的距离(hi-lo)*Math.min(height[hi],height[lo]);

• 以后两个指针开始向中间移动,先计算此时的面积,若是比以前的大,面积更新为如今的面积,以后哪个小就往中间移动哪个.直到两个相碰,中止循环.

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代码 (JavaScript)

/**
 * @param {number[]} height
 * @return {number}
 */

var maxArea = function(height) {
    let len = height.length;
    
    if (len < 2)
        return 0;
    
    let res = 0,       
        lo   = 0,         /* first pointer */
        hi   = len - 1;  /* last pointer  */
    
    while (lo < hi) {
        let area = (hi - lo) * Math.min(height[hi], height[lo]);
        res = Math.max(res, area);
        
        if (height[lo] < height[hi]) {
            lo++;
        } else {
            hi--;
        }   
    }
    
    return res;
};