Destination City

LeetCode 1436 · View on LeetCode

Find the city that has no outgoing path — it never appears as a source. Collect all sources into a set, then find the destination not in that set.

package main

import "fmt"

func destCity(paths [][]string) string {
    sources := map[string]bool{}
    for _, p := range paths {
        sources[p[0]] = true
    }
    for _, p := range paths {
        if !sources[p[1]] {
            return p[1]
        }
    }
    return ""
}

func main() {
    paths := [][]string{{"London", "New York"}, {"New York", "Lima"}, {"Lima", "Sao Paulo"}}
    fmt.Println(destCity(paths)) // Sao Paulo
}