Kotlin Kata - Single Number
Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.
You must implement a solution with a linear runtime complexity and use only constant extra space.
Example 1:
Input: nums = [2,2,1] Output: 1
Example 2:
Input: nums = [4,1,2,1,2] Output: 4
Example 3:
Input: nums = [1] Output: 1
解答
點擊展開解答
利用一個位元操作的知識
當一個數字同時和另一個數字進行兩次 xor 操作後
該數字保持不變
a xor b xor b = a
我們可以很快的解答這個題目
class Solution {
fun singleNumber(nums: IntArray): Int {
var answer = 0
for(num in nums){
answer = answer xor num
}
return answer
}
}
上述邏輯還可以用 reduce() 進行簡化
class Solution {
fun singleNumber(nums: IntArray): Int {
return nums.reduce { ans, num -> ans xor num }
}
}