數組中尋找峯值

public class Solution {

	//只存在一個峯值
    public static Integer findMaxNum(int[] nums) {
        if (nums == null || nums.length == 0) {
            return null;
        }

        int len = nums.length;
        int i = 0;
        int j = len - 1;

        while (i <= j) {
            int mid = (i + j) >> 1;
            int midNum = nums[mid];
            int leftNum = mid >= 1 ? nums[mid - 1] : midNum;
            int rightNum = mid <= len - 2 ? nums[mid + 1] : midNum;

            if (midNum >= leftNum && midNum >= rightNum) {
                return midNum;
            }

            if (leftNum <= midNum && midNum <= rightNum) {
                i = mid + 1;
            }

            if (leftNum >= midNum && midNum >= rightNum) {
                j = mid - 1;
            }
        }

        return null;
    }

    public static void main(String[] args) {
        int[][] testArray = {
                {1},
                {1, 2},
                {1, 2, 3},
                {3, 2, 1},
                {1, 2, 3, 4, 3, 2, 1},
                {1, 9, 2},
                {1, 9, 8, 7, 6, 5},
                {1, 2, 3, 8, 7}
        };

        for (int[] nums : testArray) {
            System.out.println(findMaxNum(nums));
        }
    }
}