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# 1557. Minimum Number of Vertices to Reach All Nodes

<https://leetcode.com/problems/minimum-number-of-vertices-to-reach-all-nodes>

## Description

Given a**directed acyclic graph**, with `n` vertices numbered from `0` to `n-1`, and an array `edges` where `edges[i] = [fromi, toi]` represents a directed edge from node `fromi` to node `toi`.

Find *the smallest set of vertices from which all nodes in the graph are reachable*. It's guaranteed that a unique solution exists.

Notice that you can return the vertices in any order.

**Example 1:**

![](https://assets.leetcode.com/uploads/2020/07/07/untitled22.png)

```

**Input:** n = 6, edges = [[0,1],[0,2],[2,5],[3,4],[4,2]]
**Output:** [0,3]
**Explanation:** It's not possible to reach all the nodes from a single vertex. From 0 we can reach [0,1,2,5]. From 3 we can reach [3,4,2,5]. So we output [0,3].
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2020/07/07/untitled.png)

```

**Input:** n = 5, edges = [[0,1],[2,1],[3,1],[1,4],[2,4]]
**Output:** [0,2,3]
**Explanation:** Notice that vertices 0, 3 and 2 are not reachable from any other node, so we must include them. Also any of these vertices can reach nodes 1 and 4.
```

**Constraints:**

* `2 <= n <= 10^5`
* `1 <= edges.length <= min(10^5, n * (n - 1) / 2)`
* `edges[i].length == 2`
* `0 <= fromi, toi < n`
* All pairs `(fromi, toi)` are distinct.

## ac

```java
```