二分查找一＞寻找峰值

暴力遍历：O(N),由于该题数据很少所以可以通过
        int index = 0;
        for(int i = 1; i <= nums.length-1; i++) {
            //某段区域内一直递增，更新就index
            if(nums[i] > nums[index]) index = i;
        }

        //找到并且返回
        return index;

int left = 0, right = nums.length-1;
        while(left < right){
            int mid = left + (right - left) / 2;
            if(nums[mid] > nums[mid+1]) right = mid;
            if(nums[mid] < nums[mid+1]) left = mid+1;
        }
        return left;