MonotonicArray.java

package easy;

/**
 * ClassName: MonotonicArray.java
 * Author: chenyiAlone
 * Create Time: 2019/12/20 17:50
 * Description: No.896 Monotonic Array
 *
 * 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
 *
 *
 */
public class MonotonicArray {

    public boolean isMonotonic(int[] A) {
        boolean asc = true, desc = true;
        for (int i = 1; i < A.length; i++) {
            if (A[i - 1] < A[i])
                desc = false;
            else if (A[i - 1] > A[i])
                asc = false;
            if (!desc && !asc) return false;
        }
        return true;
    }
    
}