414. Third Maximum Number

可以用priorityqueue
PriorityQueue<Integer> pq = new PriorityQueue<>();

https://leetcode.com/problems/third-maximum-number/discuss/90190/Java-PriorityQueue-O(n)-+-O(1)

 

 

//mafan Old
class Solution {
    public int thirdMax(int[] nums) {
        if(nums.length == 1) return nums[0];
        List<Integer> list = new ArrayList<Integer>();
        for(int i = 0; i < nums.length; i++) {
            if(!list.contains(nums[i])) {
                list.add(nums[i]);
            }    
        }
        int max = list.get(0);
        int fmax = 0;
        for(int j = 0; j < 2 ; j++) {
            for(int i = 0; i < list.size(); i++) {
                if(list.get(i) > max) max = list.get(i);
            }
            if(j == 0) fmax = max;
            list.remove((Integer)max);
            if(list.isEmpty()) return fmax;
            max = list.get(0);
        }
        for(int i = 0; i < list.size(); i++) {
            if(list.get(i) > max) max = list.get(i);
        }
        return max;      
        
    }
}