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pub struct Solution;
#[derive(PartialEq, Eq, Clone, Debug)]
pub struct ListNode {
pub val: i32,
pub next: Option<Box<ListNode>>,
}
#[allow(unused)]
impl ListNode {
#[inline]
fn new(val: i32) -> Self {
ListNode { next: None, val }
}
}
#[allow(unused)]
impl Solution {
pub fn reverse_list(head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
let mut head = head;
let mut pre = None;
while let Some(mut node) = head {
head = node.next.take();
node.next = pre;
pre = Some(node);
}
pre
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
let a = Some(Box::new(ListNode {
val: 1,
next: Some(Box::new(ListNode { val: 2, next: None })),
}));
let b = Some(Box::new(ListNode {
val: 2,
next: Some(Box::new(ListNode { val: 1, next: None })),
}));
assert_eq!(Solution::reverse_list(a), b);
}
}