版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/wuqingdeqing/article/details/84563673
Given an array A
of integers, return true
if and only if it is a valid mountain array.
Recall that A is a mountain array if and only if:
A.length >= 3
- There exists some
i
with0 < i < A.length - 1
such that:A[0] < A[1] < ... A[i-1] < A[i]
A[i] > A[i+1] > ... > A[B.length - 1]
Example 1:
Input: [2,1] Output: false
Example 2:
Input: [3,5,5] Output: false
Example 3:
Input: [0,3,2,1] Output: true
Note:
0 <= A.length <= 10000
0 <= A[i] <= 10000
本题逻辑比较简单,但边界条件较多,以致提交出现了不少问题。在大小反转时,应注意下标不要增加,同时规避单调递增与递减的情况。本题Accepted代码如下:
class Solution {
public boolean validMountainArray(int[] A) {
int l = A.length;
if (l < 3) {
return false;
}
int flag = 0;
for (int i = 0; i < l - 1; i++) {
if (flag == 0) {
if (A[i] >= A[i + 1]) {
if (i == 0) {
return false;
}
flag = 1;
i--;
}
} else {
if (A[i] <= A[i + 1]) {
return false;
}
}
}
if (flag == 0) {
return false;
}
return true;
}
}