【LeetCode】#137只出現一次的數字II(Single Number II)

題目描述

給定一個非空整數陣列，除了某個元素只出現一次以外，其餘每個元素均出現了三次。找出那個只出現了一次的元素。
說明：
你的演算法應該具有線性時間複雜度。 你可以不使用額外空間來實現嗎？

示例

示例 1:

輸入: [2,2,3,2]
輸出: 3

示例 2:

輸入: [0,1,0,1,0,1,99]
輸出: 99

Description

Given a non-empty array of integers, every element appears three times except for one, which appears exactly once. Find that single one.
Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

Example

Example 1:

Input: [2,2,3,2]
Output: 3

Example 2:

Input: [0,1,0,1,0,1,99]
Output: 99

解法

class Solution {
    public int singleNumber(int[] nums) {
        Arrays.sort(nums);
        int res = -1;
        for(int i=0; i<nums.length; i+=3){
            if(i==nums.length-1){
                return nums[i];
            }
            if(nums[i]!=nums[i+1]){
                res = nums[i];
                break;
            }
        }
        return res;
    }
}