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
Solution:
class Solution {
public boolean isMonotonic(int[] A) {
if (A.length <= 1) return true;
int prev = A[0];
boolean up = false;
boolean down = false;
for (int i = 1; i < A.length; i ++) {
int curr = A[i];
if (prev == curr) continue;
if (prev > curr) {
down = true;
if (up) return false;
} else {
up = true;
if (down) return false;
}
prev = curr;
}
return true;
}
}