704. Binary Search

/*
 * @lc app=leetcode id=704 lang=cpp
 *
 * [704] Binary Search
 *
 * https://leetcode.com/problems/binary-search/description/
 *
 * algorithms
 * Easy (58.66%)
 * Likes:    12543
 * Dislikes: 272
 * Total Accepted:    3.1M
 * Total Submissions: 5.3M
 * Testcase Example:  '[-1,0,3,5,9,12]\n9'
 *
 * Given an array of integers nums which is sorted in ascending order, and an
 * integer target, write a function to search target in nums. If target exists,
 * then return its index. Otherwise, return -1.
 *
 * You must write an algorithm with O(log n) runtime complexity.
 *
 *
 * Example 1:
 *
 *
 * Input: nums = [-1,0,3,5,9,12], target = 9
 * Output: 4
 * Explanation: 9 exists in nums and its index is 4
 *
 *
 * Example 2:
 *
 *
 * Input: nums = [-1,0,3,5,9,12], target = 2
 * Output: -1
 * Explanation: 2 does not exist in nums so return -1
 *
 *
 *
 * Constraints:
 *
 *
 * 1 <= nums.length <= 10^4
 * -10^4 < nums[i], target < 10^4
 * All the integers in nums are unique.
 * nums is sorted in ascending order.
 *
 *
 */

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