LeetCode-492. Construct the Rectangle (Java)

For a web developer, it is very important to know how to design a web page's size. So, given a specific rectangular web page’s area, your job by now is to design a rectangular web page, whose length L and width W satisfy the following requirements:

1. The area of the rectangular web page you designed must equal to the given target area.
2. The width W should not be larger than the length L, which means L >= W.
3. The difference between length L and width W should be as small as possible.

You need to output the length L and the width W of the web page you designed in sequence.

Example:

Input: 4Output: [2, 2]Explanation: The target area is 4, and all the possible ways to construct it are [1,4], [2,2], [4,1]. But according to requirement 2, [1,4] is illegal; according to requirement 3,  [4,1] is not optimal compared to [2,2]. So the length L is 2, and the width W is 2.

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这道题比较简单，需要了解的是循环的范围选取。代码如下：

public class Solution {    public int[] constructRectangle(int area) {        int width = 0;int length = 0;int difference = 0;int minDifference = Integer.MAX_VALUE;List<Integer> list = new ArrayList<>();        for(int i =1;i<=Math.sqrt(area);i++){        if(area%i==0){        width = i;        length = area/i;        difference = length - width;        if(difference < minDifference){        list.clear();        list.add(length);        list.add(width);        }        }        }        int [] result = new int[list.size()];        int j =0;        for(Integer value : list){        result[j++] = value;        }        return result;    }}

for循环之所以是i<=Math.sqrt(area)， 因为 num = a*b，则a,b必有一个大于根号x，有一个小于根号x，况且因子都是成对出现，所以只需判断根号x，可以减少循环次数，提高效率。