896. Monotonic Array.java

E
tags: Array

basic implementation

```

/**
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 <= A.length <= 50000
-100000 <= A[i] <= 100000
 */


class Solution {
    public boolean isMonotonic(int[] A) {
        return verify(A, true) || verify(A, false);
    }
    
    private boolean validate(int a, int b, boolean incline) {
        if (incline) return a <= b;
        return a >= b;
    }
    
    private boolean verify(int[] A, boolean incline) {
        for (int i = 0; i < A.length - 1; i++) {
            if (!validate(A[i], A[i + 1], incline)) {
                return false;
            }
        }
        return true;
    }
}
```