137. Single Number II LeetCode

Use Map

public class Solution {    public int singleNumber(int[] nums) {        Map<Integer,Integer> map = new HashMap<Integer,Integer>();        int len = nums.length;        int ans = 0;        for (int i = 0; i < len; i++){            int count = 1;            if (!map.containsKey(nums[i])) {                map.put(nums[i], count);            }            else map.put(nums[i], (map.get(nums[i]) + 1));        }        for (Map.Entry<Integer,Integer> entry : map.entrySet()){            Integer k = entry.getValue();            if (k != 3) {                ans = entry.getKey();                break;            }        }        return ans;    }}

It contains the for loop.  Map.Entry<Integer,Integer> make the traversal.