_1009.java

package com.fishercoder.solutions;

import java.util.ArrayList;
import java.util.List;

/**
 * 1009. Complement of Base 10 Integer
 *
 * Every non-negative integer N has a binary representation.
 * For example, 5 can be represented as "101" in binary,
 * 11 as "1011" in binary, and so on.
 *
 * Note that except for N = 0, there are no leading zeroes in any binary representation.
 *
 * The complement of a binary representation is the number in binary you get when
 * changing every 1 to a 0 and 0 to a 1.  For example, the complement of "101" in binary is "010" in binary.
 *
 * For a given number N in base-10, return the complement of it's binary representation as a base-10 integer.
 *
 * Example 1:
 * Input: 5
 * Output: 2
 * Explanation: 5 is "101" in binary, with complement "010" in binary, which is 2 in base-10.
 *
 * Example 2:
 * Input: 7
 * Output: 0
 * Explanation: 7 is "111" in binary, with complement "000" in binary, which is 0 in base-10.
 *
 * Example 3:
 * Input: 10
 * Output: 5
 * Explanation: 10 is "1010" in binary, with complement "0101" in binary, which is 5 in base-10.
 *
 * Note:
 * 0 <= N < 10^9
 * */
public class _1009 {
    public static class Solution1 {
        public int bitwiseComplement(int N) {
            if (N == 0) {
                return 1;
            }
            List<Integer> list = new ArrayList<>();
            while (N != 0) {
                list.add(N & 1);
                N >>= 1;
            }
            int result = 0;
            int exp = list.size() - 1;
            for (int i = list.size() - 1; i >= 0; i--) {
                if (list.get(i) == 0) {
                    result += Math.pow(2, exp);
                }
                exp--;
            }
            return result;
        }
    }
}