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LeetCode Container With Most Water

Given n non-negative integers a1a2, ..., an, where each represents a point at coordinate (iai). n vertical lines are drawn such that the two endpoints of line i is at (iai) 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.

 

题意:二维坐标系里有 n 个点 (i, ai), ai >= 0,从 (i, ai)到(i, 0)划竖线,共有 n 条竖线。
找出两条竖线,使得它们构成的矩形的面积最大,矩形的高取决于最短的竖线。
思路:贪心
从首尾两个下标head 和trail 处开始扫描,用一个变量 maxArea 保持当前最大的矩形面积。
如果head 指向的竖线短于 trail 的,则右移 head
否则左移 trail
计算面积,更新 maxArea
复杂度:时间O(n),空间O(1)

 

public class Solution {    public int maxArea(int[] height) {        if (height.length<2) {            return 0;        }                int leftEdge=0;        int rightEdge=height.length-1;        int maxarea=0,area=0;        while (leftEdge!=rightEdge) {                area=Math.min(height[leftEdge], height[rightEdge])*(rightEdge-leftEdge);                if (area>maxarea) {                    maxarea=area;                }                if (height[leftEdge]<height[rightEdge]) {                    leftEdge++;                }else {                    rightEdge--;                }        }        return maxarea;    }}

 

LeetCode Container With Most Water