LeetCode : Find Peak Element

要求$log_2n$的复杂度首先考虑二分法。

int findPeakElement(vector<int>& nums)
{
    if(nums.size() == 1)
        return nums[0];

    int begin = 0, end = nums.size() - 1;
    while(begin < end)
    {
        if(end - begin == 1)
            return nums[begin] > nums[end] ? begin : end;
        int mid = (begin + end) / 2;

        if(nums[mid] <= nums[begin])
        {
            end = mid;
            continue;
        }
        if(nums[mid] <= nums[end])
        {
            begin = mid;
            continue;
        }
        begin ++;
        end --;
    }

    return begin;
}