1466. Reorder Routes to Make All Paths Lead to the City Zero

1function minReorder(n: number, connections: number[][]): number {
2    let graph: Map<number, [number, boolean][]> = new Map();
3
4    for (const [from, to] of connections) {
5        if (!graph.has(from)) graph.set(from, [])
6        if (!graph.has(to)) graph.set(to, [])
7        graph.get(from).push([to, true])
8        graph.get(to).push([from, false])
9    }
10
11    let visisted: boolean[] = Array(n).fill(false);
12
13    function dfs(node: number): number {
14        visisted[node] = true;
15        let re_order_count = 0;
16
17        const neighbors = graph.get(node);
18        for (const [neighbor, original_direction] of neighbors) {
19            if (!visisted[neighbor]) {
20                if (original_direction) {
21                    re_order_count++
22                }
23
24                re_order_count += dfs(neighbor)
25            }
26        }
27
28        return re_order_count
29    }
30
31    return dfs(0)
32};