leetcode [#136]

目录

• 1. 题目
• 2. 解决方案
• 3. 注意事项

题目

Given an array of integers, every element appears twice except for one. Find that single one.

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解决方案

import java.util.Hashtable;
public class Solution {
    public int singleNumber(int[] nums) {
        int result = 0;
        Hashtable<Integer, Integer> table = new Hashtable<>();
        for(int i = 0; i < nums.length; i++){
            if(!table.containsKey(nums[i])){
                table.put(nums[i], 1);
            } else {
                table.put(nums[i], table.get(nums[i]) + 1);
            }
        }
        for(int k = 0; k < nums.length; k++){
            if(table.get(nums[k]) == 1) result = nums[k];
        }
        return result;
    }
}

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注意事项

1. 遍历数组，以数字元素为key，出现次数为value，构造Hashset，找出value为1的key即可。