414. 第三大的数

执行用时：28 ms, 在所有 Swift 提交中击败了86.11%的用户
内存消耗：14.1 MB, 在所有 Swift 提交中击败了13.89%的用户

class Solution {
    func thirdMax(_ nums: [Int]) -> Int {
        var sortnum = nums.sorted(by: {$0 > $1})
        let n = sortnum.count
        var diff = 1
        for i in 1 ..< n {
            if sortnum[i] != sortnum[i-1] {
                diff += 1
            }
            if diff == 3 {
                return sortnum[i]
            }
        }
        return sortnum[0]
    }
}

set去重+排序

class Solution {
    public int thirdMax(int[] nums) {
        HashSet<Integer> set = new HashSet<>();
        for (int num : nums) {
            set.add(num);
        }
        ArrayList<Integer> list = new ArrayList<>(set);
        Collections.sort(list);
        return list.size() < 3 ? list.get(list.size() - 1) : list.get(list.size()-3);
    }
}

class Solution {
    public int thirdMax(int[] nums) {
        Arrays.sort(nums);
        int diff = 1;
        int last = nums.length - 1;
        for (int i = last; i >= 1; i--) {
            if (nums[i] != nums[i-1]) {
                diff++;
            }
            if (diff == 3) {
                return nums[i-1];
            }
        }
        return nums[last];
    }
}