_852.java

package com.fishercoder.solutions;

/**852. Peak Index in a Mountain Array
 *
 * Let's call an array A a mountain if the following properties hold:
 *
 * A.length >= 3
 * There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1]
 * Given an array that is definitely a mountain, return any i such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1].
 *
 * Example 1:
 *
 * Input: [0,1,0]
 * Output: 1
 * Example 2:
 *
 * Input: [0,2,1,0]
 * Output: 1
 * Note:
 *
 * 3 <= A.length <= 10000
 * 0 <= A[i] <= 10^6
 * A is a mountain, as defined above.*/
public class _852 {
    public static class Solution1 {
        public int peakIndexInMountainArray(int[] A) {
            for (int i = 1; i < A.length - 1; i++) {
                if (A[i] > A[i + 1]) {
                    return i;
                }
            }
            return -1;
        }
    }
}