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#![allow(dead_code)]
pub fn find_peak_element(nums: Vec<i32>) -> i32 {
let mut left = 0;
let mut right = nums.len() - 1;
if nums.len() < 2 {
return 0;
}
while left < right {
let mid = (right + left) / 2;
if mid > 0 && mid + 1 < nums.len() {
if nums[mid] > nums[mid - 1] && nums[mid] > nums[mid + 1] {
return mid as i32;
}
if nums[mid] < nums[mid - 1] {
right = mid - 1;
} else {
left = mid + 1;
}
} else if mid == 0 && nums[0] > nums[1] {
return mid as i32;
} else if mid == nums.len() - 1 && nums[mid - 1] < nums[mid] {
return mid as i32;
} else {
left = mid + 1;
}
}
return left as i32;
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test1() {
assert_eq!(find_peak_element(vec![2, 1, 2]), 0);
assert_eq!(find_peak_element(vec![2, 1]), 0);
assert_eq!(find_peak_element(vec![1, 2]), 1);
assert_eq!(find_peak_element(vec![1, 2, 3]), 2);
assert_eq!(find_peak_element(vec![1, 2, 3, 1]), 2);
assert_eq!(find_peak_element(vec![1, 2, 1, 3, 5, 6, 4]), 5);
}
}