[LintCode] 585 Maximum Number in Mountain Sequence

4/23/2017

算法班

注意返回的是值，而不是index

    public int mountainSequence(int[] nums) {
        if (nums == null || nums.length == 0) return -1;
        int start = 0, end = nums.length - 1;
        int ret;
        
        while (start + 1 < end) {
            int mid = start + (end - start) / 2;
            
            if (nums[mid] > nums[mid - 1] && nums[mid] < nums[mid + 1]) return nums[mid];
            if (nums[mid] > nums[mid - 1] && nums[mid] > nums[mid + 1]) {
                end = mid;
            } else {
                start = mid;
            }
        }
        if (nums[start] < nums[end]) return nums[end];
        return nums[start];
    }