896. Monotonic Array

#### QUESTION:

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
``````

Note:

1. `1 <= A.length <= 50000`
2. `-100000 <= A[i] <= 100000`

#### EXPLANATION:

1.如果一直是升序，出现降序就直接返回false

2.如果一直是降序，出现升序就直接返回false

#### SOLUTION:

``````class Solution {
public boolean isMonotonic(int[] A) {
if(A.length<=0)return true;
int order = 0;
int pre = A[0];
for(int i = 1;i<A.length;i++){
int tmp = A[i];
if(tmp>pre && (order==0 || order == 1)){
order = 1;
pre = tmp;
continue;
}else if(tmp<pre && (order==0 || order==-1)){
order=-1;
pre=tmp;
continue;
}else if(tmp == pre){
pre=tmp;
continue;
}
return false;
}
return true;
}
}
``````
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