585. Maximum Number in Mountain Sequence [LintCode]

Given a mountain sequence of nintegers which increase firstly and then decrease, find the mountain top.

Example

Givennums=[1, 2, 4, 8, 6, 3]return8
Givennums=[10, 9, 8, 7], return10

public class Solution {
    /*
     * @param nums: a mountain sequence which increase firstly and then decrease
     * @return: then mountain top
     */
    public int mountainSequence(int[] nums) {
        // write your code here
        if (nums == null || nums.length == 0) {
            return -1;
        }
        int left = 0;
        int right = nums.length - 1;
        while (left + 1 < right) {
            int mid = left + (right - left) / 2;
            if (nums[mid] <= nums[mid + 1]) {
                left = mid;
            } else {
                right = mid;
            }
        }
        if (nums[left] >= nums[right]) {
            return nums[left];
        }
        return nums[right];
    }
}