Destination city

Array Hash Table String

79.5% acceptance

Feb 25, 2026

2310

107

You are given the array paths, where paths[i] = [cityAi, cityBi] means there exists a direct path going from cityAi to cityBi. Return the destination city, that is, the city without any path outgoing to another city. It is guaranteed that the graph of paths forms a line without any loop, therefore, there will be exactly one destination city.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

use std::collections::HashSet;
impl Solution {
  pub fn dest_city(paths: Vec<Vec<String>>) -> String {
    let outgoing: HashSet<&str> = paths.iter().map(|p| p[0].as_str()).collect();
    paths.iter().map(|p| p[1].as_str()).find(|c| !outgoing.contains(c)).unwrap().to_string()
  }
}