Leetcode 414.第三大的数

原题链接:Leetcode 414. Third Maximum Number

Given an integer array nums, return the third distinct maximum number in this array. If the third maximum does not exist, return the maximum number.

Example 1:

Input: nums = [3,2,1]

Output: 1

Explanation:

The first distinct maximum is 3.

The second distinct maximum is 2.

The third distinct maximum is 1.

Example 2:

Input: nums = [1,2]

Output: 2

Explanation:

The first distinct maximum is 2.

The second distinct maximum is 1.

The third distinct maximum does not exist, so the maximum (2) is returned instead.

Example 3:

Input: nums = [2,2,3,1]

Output: 1

Explanation:

The first distinct maximum is 3.

The second distinct maximum is 2 (both 2's are counted together since they have the same value).

The third distinct maximum is 1.

Constraints:

  • 1 <= nums.length <= 104
  • -231 <= nums[i] <= 231 - 1

Follow up: Can you find an O(n) solution?


方法一:遍历数组

思路:

题目要求返回第三大的数,以及当没有三个不同数的情况下返回第二个数

那么就维护三个值:first、second、third,最后分情况返回即可

比较麻烦的就是初始值,需要设置一个最小的正数,这里用 LONG_LONG_MIN

C++ 代码:

cpp 复制代码
class Solution {
public:
    // const long long Min = -(1LL << 31) - 1;
    int thirdMax(vector<int>& nums) {
        long first = LONG_LONG_MIN, second = LONG_LONG_MIN, third = LONG_LONG_MIN;    // 当前最大的三个数
        
        // 遍历的同时维护这三个数
        for(int i = 0; i < nums.size(); i++ ){
            if(nums[i] > first){
                third = second;
                second = first;
                first = nums[i];
            }
            else if(nums[i] < first && nums[i] > second){
                third = second;
                second = nums[i];
            }
            else if(nums[i] < second && nums[i] > third){
                third = nums[i];
            }
        }

        if(third == LONG_LONG_MIN)
            return first;
        return third;
    }
};
相关推荐
三维重建-光栅投影1 小时前
VS中将cuda项目编译为DLL并调用
算法
课堂剪切板3 小时前
ch03 部分题目思路
算法
山登绝顶我为峰 3(^v^)34 小时前
如何录制带备注的演示文稿(LaTex Beamer + Pympress)
c++·线性代数·算法·计算机·密码学·音视频·latex
Two_brushes.5 小时前
【算法】宽度优先遍历BFS
算法·leetcode·哈希算法·宽度优先
森焱森7 小时前
水下航行器外形分类详解
c语言·单片机·算法·架构·无人机
QuantumStack9 小时前
【C++ 真题】P1104 生日
开发语言·c++·算法
写个博客10 小时前
暑假算法日记第一天
算法
绿皮的猪猪侠10 小时前
算法笔记上机训练实战指南刷题
笔记·算法·pta·上机·浙大
hie9889411 小时前
MATLAB锂离子电池伪二维(P2D)模型实现
人工智能·算法·matlab
杰克尼11 小时前
BM5 合并k个已排序的链表
数据结构·算法·链表