[JS] Find Minimum in Rotated Sorted Array

🔒 문제 (LeetCode 153)

Suppose an array of length n sorted in ascending order is rotated between 1 and n times. For example, the array nums = [0,1,2,4,5,6,7] might become:

• [4,5,6,7,0,1,2] if it was rotated 4 times.
• [0,1,2,4,5,6,7] if it was rotated 7 times.

Notice that rotating an array [a[0], a[1], a[2], ..., a[n-1]] 1 time results in the array [a[n-1], a[0], a[1], a[2], ..., a[n-2]].

Given the sorted rotated array nums of unique elements, return the minimum element of this array.

You must write an algorithm that runs in O(log n) time.

Constraints:

• n == nums.length
• 1 <= n <= 5000
• -5000 <= nums[i] <= 5000
• All the integers of nums are unique.
• nums is sorted and rotated between 1 and n times.

 

🌊 입출력

Example 1:

Input: nums = [3,4,5,1,2]
Output: 1
Explanation: The original array was [1,2,3,4,5] rotated 3 times.

Example 2:

Input: nums = [4,5,6,7,0,1,2]
Output: 0
Explanation: The original array was [0,1,2,4,5,6,7] and it was rotated 4 times.

Example 3:

Input: nums = [11,13,15,17]
Output: 11
Explanation: The original array was [11,13,15,17] and it was rotated 4 times. 

 

---

 

🔑 해결

🌌 알고리즘 - 이분탐색

/**
 * @param {number[]} nums
 * @return {number}
 */
var findMin = function(nums) {
    let l = 0;
    let r = nums.length - 1;
    
    while(l < r) {
        let mid = l + r >>> 1;

        if(nums[mid] > nums[r]) {
            l = mid + 1;
        } else {
            r = mid;
        }
    }
    return nums[l];
};