33.search-in-rotated-sorted-array.cpp

/*
 * @lc app=leetcode id=33 lang=cpp
 *
 * [33] Search in Rotated Sorted Array
 *
 * https://leetcode.com/problems/search-in-rotated-sorted-array/description/
 *
 * algorithms
 * Medium (32.66%)
 * Total Accepted:    373.9K
 * Total Submissions: 1.1M
 * Testcase Example:  '[4,5,6,7,0,1,2]\n0'
 *
 * Suppose an array sorted in ascending order is rotated at some pivot unknown
 * to you beforehand.
 *
 * (i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).
 *
 * You are given a target value to search. If found in the array return its
 * index, otherwise return -1.
 *
 * You may assume no duplicate exists in the array.
 *
 * Your algorithm's runtime complexity must be in the order of O(log n).
 *
 * Example 1:
 *
 *
 * Input: nums = [4,5,6,7,0,1,2], target = 0
 * Output: 4
 *
 *
 * Example 2:
 *
 *
 * Input: nums = [4,5,6,7,0,1,2], target = 3
 * Output: -1
 *
 */
#include <vector>
using namespace std;

class Solution
{
  public:
    int search(vector<int> &nums, int target)
    {
        int left = 0;
        int right = nums.size() - 1;
        int mid, result;
        while (left <= right)
        {
            mid = left + (right - left) / 2;
            if (nums[mid] == target)
                return mid;
            if (nums[left] < nums[right])
            {
                if (target < nums[mid])
                    right = mid - 1;
                else
                    left = mid + 1;
            }
            else
            {
                if ((nums[left] <= target && (target < nums[mid] || nums[mid] < nums[right])) || (target <= nums[mid] && nums[mid] <= nums[right]))
                    right = mid - 1;
                else
                    left = mid + 1;
            }
        }
        return -1;
    }
};