leetCode/SingleNumber2.java at master · rahul-tasker/leetCode · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
/*
Given a non-empty array of integers, every element appears three times except for one, which appears exactly once. Find that single one.

Example 1:

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

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

Runtime: 6 ms, faster than 25.71% of Java online submissions
*/

class Solution {
    public int singleNumber(int[] nums) {
        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
        for(int i = 0; i < nums.length; i ++) {
            if(map.containsKey(nums[i])) {
                map.put(nums[i], map.get(nums[i]) + 1);
            } else {
                map.put(nums[i], 1);
            }
        }
        for(Integer key : map.keySet()) {
            if(map.get(key) == 1) {
                return key;
            }
        }
        return -1;
    }
}