光纖通訊 - Problem

#22809. 光纖通訊

Statistics

Farmer John 想用新光纖網路連接 $N$ 座穀倉（$1 \le N \le 1{,}000$），編號 $1..N$。穀倉沿大池塘邊圍成圈，因此只能連相鄰穀倉；穀倉 $N$ 與 1 相鄰。

不必連通全部穀倉，因為只有特定牛對想通訊。他希望連線盡量少，又讓所有需求對透過網路通訊。給定這些穀倉對，求至少鋪設幾條線路。從 1 到 3 通訊，要鋪設 1 到 2、2 到 3 的線路。

輸入格式

第 $1$ 行：整數 $N$、$P$，後者為通訊對數（$1 \le P \le 10{,}000$）。
第 $2..P+1$ 行：兩個整數，表示希望通訊的一對穀倉；列表沒有重複對。

輸出格式

一行一個整數，FJ 所需最少直接連線數。

範例

輸入格式 1

5 2
1 3
4 5

輸出格式 1

說明

這些線路連接穀倉對 1-2、2-3、4-5。

題目來源：Reid Barton，2001。

Discussions

About Discussions

The discussion section is only for posting: General Discussions (problem-solving strategies, alternative approaches), and Off-topic conversations.

This is NOT for reporting issues! If you want to report bugs or errors, please use the Issues section below.

Open Discussions 0

No discussions in this category.

Issues

About Issues

If you find any issues with the problem (statement, scoring, time/memory limits, test cases, etc.), you may submit an issue here. A problem moderator will review your issue.

Guidelines:

This is not a place to publish discussions, editorials, or requests to debug your code. Issues are only visible to you and problem moderators.
Do not submit duplicated issues.
Issues must be filed in English or Chinese only.

Active Issues 0

No issues in this category.

Closed/Resolved Issues 0