153. Find Minimum in Rotated Sorted Array

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, return the minimum element of this array.

 

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. 

 

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.

Rust Solution

struct Solution;

impl Solution {
    fn find_min(nums: Vec<i32>) -> i32 {
        let mut l = 0;
        let mut h = nums.len() - 1;
        while l < h {
            if nums[l] < nums[h] {
                return nums[l];
            }
            let m = l + (h - l) / 2;
            if nums[l] <= nums[m] {
                l = m + 1;
            } else {
                h = m;
            }
        }
        nums[l]
    }
}

#[test]
fn test() {
    let nums = vec![3, 4, 5, 1, 2];
    let res = 1;
    assert_eq!(Solution::find_min(nums), res);
    let nums = vec![4, 5, 6, 7, 0, 1, 2];
    let res = 0;
    assert_eq!(Solution::find_min(nums), res);
}

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