Given an array of distinct integers arr, where arr is sorted in ascending order, return the smallest index i that satisfies arr[i] == i. If there is no such index, return -1.
Example 1:
Input: arr = [-10,-5,0,3,7]
Output: 3
Explanation: For the given array, arr[0] = -10, arr[1] = -5, arr[2] = 0, arr[3] = 3, thus the output is 3.
Example 2:
Input: arr = [0,2,5,8,17]
Output: 0
Explanation: arr[0] = 0, thus the output is 0.
Example 3:
Input: arr = [-10,-5,3,4,7,9] Output: -1 Explanation: There is no suchithatarr[i] == i, thus the output is -1.
Constraints:
1 <= arr.length < 104-109 <= arr[i] <= 109Follow up: The
O(n) solution is very straightforward. Can we do better?struct Solution;
impl Solution {
fn fixed_point(a: Vec<i32>) -> i32 {
for i in 0..a.len() {
if i as i32 == a[i] {
return i as i32;
}
}
-1
}
}
#[test]
fn test() {
assert_eq!(Solution::fixed_point(vec![-10, -5, 0, 3, 7]), 3);
assert_eq!(Solution::fixed_point(vec![0, 2, 5, 8, 17]), 0);
assert_eq!(Solution::fixed_point(vec![-10, -5, 3, 4, 7, 9]), -1);
}