描述
An array is monotonic if it is either monotone increasing or monotone decreasing.
An array A is monotone increasing if for all i <= j, A[i] <= A[j]. An array A is monotone decreasing if for all i <= j, A[i] >= A[j].
Return true if and only if the given array A is monotonic.
Example 1:
Input: [1,2,2,3]
Output: true
Example 2:
Input: [6,5,4,4]
Output: true
Example 3:
Input: [1,3,2]
Output: false
Example 4:
Input: [1,2,4,5]
Output: true
Example 5:
Input: [1,1,1]
Output: true
思路
这个题目很简单，只要数组全部是递增的，或者是递减的（不是严格意义上的递增递减，即，可以允许等于存在），就是true。我们设俩标志位，检查是否满足递增递减就好。
代码
class Solution {
public:
bool isMonotonic(vector<int>& A) {
bool creasing = true;
bool decreasing = true;
for(int i = 0; i < A.size()-1; i++)
{
if(A[i]>A[i+1])
creasing = false;
if(A[i]<A[i+1])
decreasing = false;
}
return creasing || decreasing;
}
};
