Implemented p24, changed linked_list impotr to always use crate in its path instead of super, modified p19
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4 changed files with 50 additions and 17 deletions
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@ -23,3 +23,4 @@ pub mod p20_valid_parentheses;
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pub mod p21_merge_two_sorted_lists;
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pub mod p22_generate_parentheses;
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pub mod p23_merge_k_sorted_lists;
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pub mod p24_swap_nodes_in_pairs;
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@ -1,26 +1,24 @@
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use super::linked_list::ListNode;
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use crate::linked_list::ListNode;
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pub struct Solution;
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impl Solution {
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pub fn remove_nth_from_end(head: Option<Box<ListNode>>, n: i32) -> Option<Box<ListNode>> {
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let mut head = head.unwrap();
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let mut node_before_nth: &mut Box<ListNode>;
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let mut dummy = Some(Box::new(ListNode { val: 0, next: head }));
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let mut node_before_nth: &mut Option<Box<ListNode>>;
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// unsafe is required to have immutable and mutable references at the same time
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// in order to avoid cloning the list altogether
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unsafe { node_before_nth = &mut *(&mut head as *mut Box<ListNode>); };
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let mut tail = &head;
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for _ in 0..n-1 {
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tail = tail.next.as_ref().unwrap();
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// in order to avoid cloning the list
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unsafe { node_before_nth = &mut *(&mut dummy as *mut Option<Box<ListNode>>); };
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let mut tail = &dummy.as_ref().unwrap().next;
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for _ in 0..n {
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tail = &tail.as_ref().unwrap().next;
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}
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if tail.next.is_none() { return head.next; }
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else { tail = tail.next.as_ref().unwrap(); }
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while tail.next.is_some() {
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tail = tail.next.as_ref().unwrap();
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node_before_nth = node_before_nth.next.as_mut().unwrap();
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while tail.is_some() {
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tail = &tail.as_ref().unwrap().next;
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node_before_nth = &mut node_before_nth.as_mut().unwrap().next;
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}
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let node_to_remove = node_before_nth.next.as_mut().unwrap();
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node_before_nth.next = node_to_remove.next.take();
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return Some(head);
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let node_to_remove = &mut node_before_nth.as_mut().unwrap().next;
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node_before_nth.as_mut().unwrap().next = node_to_remove.as_mut().unwrap().next.take();
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return dummy.unwrap().next;
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}
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}
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34
src/p24_swap_nodes_in_pairs.rs
Normal file
34
src/p24_swap_nodes_in_pairs.rs
Normal file
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@ -0,0 +1,34 @@
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use crate::linked_list::ListNode;
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pub struct Solution;
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impl Solution {
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pub fn swap_pairs(mut head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
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if head.is_none() { return None; }
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let mut tail = &mut head;
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while tail.is_some() {
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let next = &mut tail.as_mut().unwrap().next;
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if next.is_none() { break; }
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let mut next_node = next.take();
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tail.as_mut().unwrap().next = next_node.as_mut().unwrap().next.take();
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next_node.as_mut().unwrap().next = tail.take();
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tail.replace(next_node.unwrap());
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tail = &mut tail.as_mut().unwrap().next.as_mut().unwrap().next;
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}
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return head;
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}
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}
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#[test]
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fn test1() {
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assert_eq!(Solution::swap_pairs(list![1,2,3,4]), list![2,1,4,3]);
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}
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#[test]
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fn test2() {
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assert_eq!(Solution::swap_pairs(list![]), list![]);
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}
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#[test]
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fn test3() {
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assert_eq!(Solution::swap_pairs(list![1]), list![1]);
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}
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@ -1,4 +1,4 @@
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use super::linked_list::ListNode;
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use crate::linked_list::ListNode;
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pub struct Solution;
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impl Solution {
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