[C#][LeetCode][Easy] 476. Number Complement

心得:

題目要求將數字轉換為其補數,看起來滿單純的我就想不開硬幹了,由於不想借助C#內建的方法,所以自己實作二進位與十進位之間轉換。

題目:

Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.

Note:

  1. The given integer is guaranteed to fit within the range of a 32-bit signed integer.
  2. You could assume no leading zero bit in the integer’s binary representation.

答案:

  1. Normal – 硬幹
    public class Solution {
        public int FindComplement(int num) {
            string str = ConvertMethod(num);
            string ans = "";
            for(int i = 0; i < str.Length; i++){
                if(str[i] == '0'){
                    ans += "1";
                }else{
                    ans += "0";
                }
            }
            
            return ConvertMethod(ans);
        }
        
        private string ConvertMethod(int num){
            string str = "";
            while (num > 1)
            {
                str = num % 2 + str;
                num = num / 2;
                if (num == 1)
                {
                    str = num + str;
                    num = 0;
                }
            }
            
            return str;
        }
        
        private int ConvertMethod(string str)
        {
            int ans = 0;
            for (int i = 0; i < str.Length; i++)
            {
                int tmp = 1;
                for (int j = 1; j < (str.Length - i); j++)
                {
                    tmp *= 2;
                }
                ans += tmp * int.Parse(str[i].ToString());
            }
    
            return ans;
        }
    }
  2. LinQ
    public class Solution {
        public int FindComplement(int num) {
            return Convert.ToInt32(new string(Convert.ToString(num, 2).Select(x => x == '1' ? '0' : '1').ToArray()), 2);
        }
    }

參考:

  1. http://www.sggs.hc.edu.tw/sggsnew/comp/bccto2816.htm
  2. [C#] 轉2進位 / 10進位 / 16進位


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