845. Longest Mountain in Array

Posted on | In , |

题目

https://leetcode.com/problems/longest-mountain-in-array/description/

-w949

想法

描述清楚不难，但是用一个巧妙简洁的方式叙述出来，可就没有那么容易了

蛮有趣的一个题目

答案

借鉴自：
https://leetcode.com/problems/longest-mountain-in-array/discuss/135593/C++JavaPython-1-pass-and-O(1)-space

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
class Solution {
public:
    int longestMountain(vector<int>& A) {
        int up = 0, down = 0;
        int res = 0;
        for (int i = 1; i < A.size(); i++) {
            if (down && A[i] > A[i - 1] || A[i] == A[i - 1])
                up = down = 0;
            if (A[i] > A[i - 1])
                up++;
            else if (A[i] < A[i - 1])
                down++;
            if (up && down)
                res = max(res, up + down + 1);
        }
        return res;
    }
};