心得

簡單來說就是輸入數字x，找出x的因數並找出相乘會等於x的兩個數字且兩數字相減最接近0的組合，大的放前面小的放後面以int[]的型態回傳。

問題

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.

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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: 4 Output: [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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Input: 4 Output: [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.

Note:

1. The given area won’t exceed 10,000,000 and is a positive integer
2. The web page’s width and length you designed must be positive integers.

答案

1. 我的笨方法
   
   C#

   public class Solution { public int[] ConstructRectangle(int area) { int num1 = Enumerable .Range(1, (int)Math.Sqrt(area)) .Where(x => area % x == 0) .OrderBy(x => Math.Abs((area / x) - x)) .FirstOrDefault(); int num2 = area / num1; return num1 > num2 ? new int[] { num1, num2 } : new int[] { num2, num1 }; } }

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   public class Solution {     public int[] ConstructRectangle(int area) {         int num1 = Enumerable             .Range(1, (int)Math.Sqrt(area))             .Where(x => area % x == 0)             .OrderBy(x => Math.Abs((area / x) - x))             .FirstOrDefault();         int num2 = area / num1;         return num1 > num2 ? new int[] { num1, num2 } : new int[] { num2, num1 };     } }

2. Top Solution的神方法
   
   C#

   public class Solution { public int[] ConstructRectangle(int area) { int w = (int)Math.Sqrt(area); while( area % w != 0){ w--; } return new int[] { area / w, w }; } }

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   public class Solution {     public int[] ConstructRectangle(int area) {         int w = (int)Math.Sqrt(area);         while( area % w != 0){             w--;         }         return new int[] { area / w, w };     } }