332. Reconstruct Itinerary
Given a list of airline tickets represented by pairs of departure and arrival airports [from, to]
, reconstruct the itinerary in order. All of the tickets belong to a man who departs from JFK
. Thus, the itinerary must begin with JFK
.
Note:
- If there are multiple valid itineraries, you should return the itinerary that has the smallest lexical order when read as a single string. For example, the itinerary
["JFK", "LGA"]
has a smaller lexical order than["JFK", "LGB"]
. - All airports are represented by three capital letters (IATA code).
- You may assume all tickets form at least one valid itinerary.
- One must use all the tickets once and only once.
Example 1:
Input:
[["MUC", "LHR"], ["JFK", "MUC"], ["SFO", "SJC"], ["LHR", "SFO"]]
Output:["JFK", "MUC", "LHR", "SFO", "SJC"]
Example 2:
Input:
[["JFK","SFO"],["JFK","ATL"],["SFO","ATL"],["ATL","JFK"],["ATL","SFO"]]
Output:["JFK","ATL","JFK","SFO","ATL","SFO"]
Explanation: Another possible reconstruction is["JFK","SFO","ATL","JFK","ATL","SFO"]
. But it is larger in lexical order.
Rust Solution
struct Solution;
use std::cmp::Reverse;
use std::collections::BinaryHeap;
use std::collections::HashMap;
type G = HashMap<String, BinaryHeap<Reverse<String>>>;
impl Solution {
fn find_itinerary(tickets: Vec<Vec<String>>) -> Vec<String> {
let mut res: Vec<String> = vec![];
let mut g: G = HashMap::new();
for ticket in tickets {
g.entry(ticket[0].clone())
.or_default()
.push(Reverse(ticket[1].clone()));
}
let mut stack: Vec<String> = vec![];
stack.push("JFK".to_string());
while !stack.is_empty() {
while g.contains_key(stack.last().unwrap())
&& !g.get(stack.last().unwrap()).unwrap().is_empty()
{
let airports = g.get_mut(stack.last().unwrap()).unwrap();
let airport = airports.pop().unwrap().0;
stack.push(airport);
}
res.insert(0, stack.pop().unwrap());
}
res
}
}
#[test]
fn test() {
let tickets: Vec<Vec<String>> = vec_vec_string![
["MUC", "LHR"],
["JFK", "MUC"],
["SFO", "SJC"],
["LHR", "SFO"]
];
let res: Vec<String> = vec_string!["JFK", "MUC", "LHR", "SFO", "SJC"];
assert_eq!(Solution::find_itinerary(tickets), res);
}
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