685 - First Unique Number In Stream

2017.9.29

这个题目是要求输出第一个非唯一的元素。如果直接用HashMap的话会失去顺序，所以需要使用LinkedHashMap。

public class Solution {
    /*
     * @param : a continuous stream of numbers
     * @param : a number
     * @return: returns the first unique number
     */
  	public int firstUniqueNumber(int[] nums, int number) {
        // Write your code here
		if(nums == null){
			return -1;
		}
		int res = -1;
		LinkedHashMap<Integer,Integer> map = new LinkedHashMap<>();
		boolean find = false;
		for(int i = 0; i < nums.length; i++){
			if(nums[i] == number){
				find = true;
				break;
			}
			if(!map.containsKey(nums[i])){
				map.put(nums[i], 1);
			}
			else{
				map.put(nums[i], map.get(nums[i]) + 1);
			}
		}
		if(find == false){
			return res;
		}
		Iterator ite = map.keySet().iterator();
		while(ite.hasNext()){
			int tmp = (int)ite.next();
			if(map.get(tmp) == 1){
				res = tmp;
				break;
			}
		}
		return res;
    }
};