Leetcode刷题

Problem 136

Posted by Ruizhi Ma on October 26, 2020

Solution URL

https://leetcode.com/submissions/detail/413588394/

代码

class Solution {
    public int singleNumber(int[] nums) {
//         //HashMap法
//         Map<Integer, Integer> map = new HashMap<>();
//         //遍历nums，将num和出现的频率以k-v保存
//         for(int num: nums){
//             map.put(num, map.getOrDefault(num, 0) + 1);
//         }

//         //遍历map，找到v为1的k
//         int res = 0;
//         for(Integer key: map.keySet()){
//             if(map.get(key) == 1) res = key;
//         }

//         return res;

        //异或法
        //ans： https://leetcode-cn.com/problems/single-number/solution/xue-suan-fa-jie-guo-xiang-dui-yu-guo-cheng-bu-na-y/
        int ans = nums[0];

        if(nums.length > 1){
            for(int i = 1; i < nums.length; i++){
                ans ^= nums[i];
            }
        }

        return ans;
    }
}