[C#][LeetCode][Easy] 492. Construct the Rectangle

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:

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

Example:

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Input: 4
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> Output: [2, 2]
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> Explanation: The target area is 4, and all the possible ways to construct it are [1,4], [2,2], [4,1].
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> 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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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
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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 };
}
}
  1. Top Solution的神方法
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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 };
}
}