Blocked Roads

AtCoder

IDabc218_f

Time2000ms

Memory256MB

Difficulty—

You are given a directed graph with $N$ vertices and $M$ edges. The vertices are numbered $1$ through $N$, and the edges are numbered $1$ through $M$. Edge $i$ $(1 \leq i \leq M)$ goes from Vertex $s_i$ to Vertex $t_i$ and has a length of $1$. For each $i$ $(1 \leq i \leq M)$, find the shortest distance from Vertex $1$ to Vertex $N$ when all edges except Edge $i$ are passable, or print `-1` if Vertex $N$ is unreachable from Vertex $1$. ## Constraints * $2 \leq N \leq 400$ * $1 \leq M \leq N(N-1)$ * $1 \leq s_i,t_i \leq N$ * $s_i \neq t_i$ * $(s_i,t_i) \neq (s_j,t_j)$ $(i \neq j)$ * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ $M$ $s_1$ $t_1$ $s_2$ $t_2$ $\vdots$ $s_M$ $t_M$ [samples]

Samples

Input #1

Output #1

1
2
1

Input #2

Output #2

\-1
2
3
2

Vertex $N$ is unreachable from Vertex $1$ when all edges except Edge $1$ are passable, so the corresponding line contains `-1`.

Input #3

Output #3

Input #4

4 1
1 2

Output #4

\-1

API Response (JSON)

{
  "problem": {
    "name": "Blocked Roads",
    "description": {
      "content": "You are given a directed graph with $N$ vertices and $M$ edges. The vertices are numbered $1$ through $N$, and the edges are numbered $1$ through $M$. Edge $i$ $(1 \\leq i \\leq M)$ goes from Vertex $s_",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc218_f"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "You are given a directed graph with $N$ vertices and $M$ edges. The vertices are numbered $1$ through $N$, and the edges are numbered $1$ through $M$. Edge $i$ $(1 \\leq i \\leq M)$ goes from Vertex $s_...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments